Dart null safety (#6696)

* Dart null-safety - prepare migration annotations in library files

* Dart null-safety - apply migration

* Dart null-safety - update flatc to generate valid code

* Dart null-safety - fix flatc generated code and adjust tests

* Dart null-safety - update example and the generated code in the tests folder

* Dart null safety - minor review changes

* Dart - apply `dartfmt -w .`

14 files changed, 2448 insertions, 1559 deletions

diff --git a/dart/example/example.dart b/dart/example/example.dart
index d95bb31f..c84ffa60 100644
--- a/dart/example/example.dart
+++ b/dart/example/example.dart
@@ -26,10 +26,10 @@ void main() {
 
 void builderTest() {
   final builder = new fb.Builder(initialSize: 1024);
-  final int weaponOneName = builder.writeString("Sword");
+  final int? weaponOneName = builder.writeString("Sword");
   final int weaponOneDamage = 3;
 
-  final int weaponTwoName = builder.writeString("Axe");
+  final int? weaponTwoName = builder.writeString("Axe");
   final int weaponTwoDamage = 5;
 
   final swordBuilder = new myGame.WeaponBuilder(builder)
@@ -45,7 +45,7 @@ void builderTest() {
   final int axe = axeBuilder.finish();
 
   // Serialize a name for our monster, called "Orc".
-  final int name = builder.writeString('Orc');
+  final int? name = builder.writeString('Orc');
 
   // Create a list representing the inventory of the Orc. Each number
   // could correspond to an item that can be claimed after he is slain.
@@ -122,27 +122,25 @@ bool verify(List<int> buffer) {
   assert(monster.name == "MyMonster");
 
   // Get and test a field of the FlatBuffer's `struct`.
-  var pos = monster.pos;
-  assert(pos != null);
+  var pos = monster.pos!;
   assert(pos.z == 3.0);
 
   // Get a test an element from the `inventory` FlatBuffer's `vector`.
-  var inv = monster.inventory;
-  assert(inv != null);
+  var inv = monster.inventory!;
   assert(inv.length == 10);
   assert(inv[9] == 9);
 
   // Get and test the `weapons` FlatBuffers's `vector`.
   var expected_weapon_names = ["Sword", "Axe"];
   var expected_weapon_damages = [3, 5];
-  var weps = monster.weapons;
+  var weps = monster.weapons!;
   for (int i = 0; i < weps.length; i++) {
     assert(weps[i].name == expected_weapon_names[i]);
     assert(weps[i].damage == expected_weapon_damages[i]);
   }
 
   // Get and test the `Equipment` union (`equipped` field).
-  assert(monster.equippedType.value == myGame.EquipmentTypeId.Weapon.value);
+  assert(monster.equippedType!.value == myGame.EquipmentTypeId.Weapon.value);
   assert(monster.equippedType == myGame.EquipmentTypeId.Weapon);
 
   assert(monster.equipped is myGame.Weapon);
diff --git a/dart/example/monster_my_game.sample_generated.dart b/dart/example/monster_my_game.sample_generated.dart
index ced9b31b..4f08860f 100644
--- a/dart/example/monster_my_game.sample_generated.dart
+++ b/dart/example/monster_my_game.sample_generated.dart
@@ -1,5 +1,5 @@
 // automatically generated by the FlatBuffers compiler, do not modify
-// ignore_for_file: unused_import, unused_field, unused_local_variable
+// ignore_for_file: unused_import, unused_field, unused_element, unused_local_variable
 
 library my_game.sample;
 
@@ -12,13 +12,16 @@ class Color {
   const Color._(this.value);
 
   factory Color.fromValue(int value) {
-    if (value == null) value = 0;
-    if (!values.containsKey(value)) {
+    final result = values[value];
+    if (result == null) {
       throw new StateError('Invalid value $value for bit flag enum Color');
     }
-    return values[value];
+    return result;
   }
 
+  static Color? _createOrNull(int? value) => 
+      value == null ? null : Color.fromValue(value);
+
   static const int minValue = 0;
   static const int maxValue = 2;
   static bool containsValue(int value) => values.containsKey(value);
@@ -26,7 +29,10 @@ class Color {
   static const Color Red = const Color._(0);
   static const Color Green = const Color._(1);
   static const Color Blue = const Color._(2);
-  static const Map<int,Color> values = {0: Red,1: Green,2: Blue,};
+  static const Map<int, Color> values = {
+    0: Red,
+    1: Green,
+    2: Blue};
 
   static const fb.Reader<Color> reader = const _ColorReader();
 
@@ -52,20 +58,25 @@ class EquipmentTypeId {
   const EquipmentTypeId._(this.value);
 
   factory EquipmentTypeId.fromValue(int value) {
-    if (value == null) value = 0;
-    if (!values.containsKey(value)) {
+    final result = values[value];
+    if (result == null) {
       throw new StateError('Invalid value $value for bit flag enum EquipmentTypeId');
     }
-    return values[value];
+    return result;
   }
 
+  static EquipmentTypeId? _createOrNull(int? value) => 
+      value == null ? null : EquipmentTypeId.fromValue(value);
+
   static const int minValue = 0;
   static const int maxValue = 1;
   static bool containsValue(int value) => values.containsKey(value);
 
   static const EquipmentTypeId NONE = const EquipmentTypeId._(0);
   static const EquipmentTypeId Weapon = const EquipmentTypeId._(1);
-  static const Map<int,EquipmentTypeId> values = {0: NONE,1: Weapon,};
+  static const Map<int, EquipmentTypeId> values = {
+    0: NONE,
+    1: Weapon};
 
   static const fb.Reader<EquipmentTypeId> reader = const _EquipmentTypeIdReader();
 
@@ -116,9 +127,7 @@ class _Vec3Reader extends fb.StructReader<Vec3> {
 }
 
 class Vec3Builder {
-  Vec3Builder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  Vec3Builder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -137,9 +146,9 @@ class Vec3ObjectBuilder extends fb.ObjectBuilder {
   final double _z;
 
   Vec3ObjectBuilder({
-    double x,
-    double y,
-    double z,
+    required double x,
+    required double y,
+    required double z,
   })
       : _x = x,
         _y = y,
@@ -147,10 +156,7 @@ class Vec3ObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     fbBuilder.putFloat32(_z);
     fbBuilder.putFloat32(_y);
     fbBuilder.putFloat32(_x);
@@ -159,7 +165,7 @@ class Vec3ObjectBuilder extends fb.ObjectBuilder {
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -177,21 +183,21 @@ class Monster {
   final fb.BufferContext _bc;
   final int _bcOffset;
 
-  Vec3 get pos => Vec3.reader.vTableGet(_bc, _bcOffset, 4, null);
+  Vec3? get pos => Vec3.reader.vTableGetNullable(_bc, _bcOffset, 4);
   int get mana => const fb.Int16Reader().vTableGet(_bc, _bcOffset, 6, 150);
   int get hp => const fb.Int16Reader().vTableGet(_bc, _bcOffset, 8, 100);
-  String get name => const fb.StringReader().vTableGet(_bc, _bcOffset, 10, null);
-  List<int> get inventory => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGet(_bc, _bcOffset, 14, null);
-  Color get color => new Color.fromValue(const fb.Int8Reader().vTableGet(_bc, _bcOffset, 16, 2));
-  List<Weapon> get weapons => const fb.ListReader<Weapon>(Weapon.reader).vTableGet(_bc, _bcOffset, 18, null);
-  EquipmentTypeId get equippedType => new EquipmentTypeId.fromValue(const fb.Uint8Reader().vTableGet(_bc, _bcOffset, 20, 0));
-  dynamic get equipped {
+  String? get name => const fb.StringReader().vTableGetNullable(_bc, _bcOffset, 10);
+  List<int>? get inventory => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGetNullable(_bc, _bcOffset, 14);
+  Color get color => Color.fromValue(const fb.Int8Reader().vTableGet(_bc, _bcOffset, 16, 2));
+  List<Weapon>? get weapons => const fb.ListReader<Weapon>(Weapon.reader).vTableGetNullable(_bc, _bcOffset, 18);
+  EquipmentTypeId? get equippedType => EquipmentTypeId._createOrNull(const fb.Uint8Reader().vTableGetNullable(_bc, _bcOffset, 20));
+  dynamic? get equipped {
     switch (equippedType?.value) {
-      case 1: return Weapon.reader.vTableGet(_bc, _bcOffset, 22, null);
+      case 1: return Weapon.reader.vTableGetNullable(_bc, _bcOffset, 22);
       default: return null;
     }
   }
-  List<Vec3> get path => const fb.ListReader<Vec3>(Vec3.reader).vTableGet(_bc, _bcOffset, 24, null);
+  List<Vec3>? get path => const fb.ListReader<Vec3>(Vec3.reader).vTableGetNullable(_bc, _bcOffset, 24);
 
   @override
   String toString() {
@@ -208,9 +214,7 @@ class _MonsterReader extends fb.TableReader<Monster> {
 }
 
 class MonsterBuilder {
-  MonsterBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  MonsterBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -222,39 +226,39 @@ class MonsterBuilder {
     fbBuilder.addStruct(0, offset);
     return fbBuilder.offset;
   }
-  int addMana(int mana) {
+  int addMana(int? mana) {
     fbBuilder.addInt16(1, mana);
     return fbBuilder.offset;
   }
-  int addHp(int hp) {
+  int addHp(int? hp) {
     fbBuilder.addInt16(2, hp);
     return fbBuilder.offset;
   }
-  int addNameOffset(int offset) {
+  int addNameOffset(int? offset) {
     fbBuilder.addOffset(3, offset);
     return fbBuilder.offset;
   }
-  int addInventoryOffset(int offset) {
+  int addInventoryOffset(int? offset) {
     fbBuilder.addOffset(5, offset);
     return fbBuilder.offset;
   }
-  int addColor(Color color) {
+  int addColor(Color? color) {
     fbBuilder.addInt8(6, color?.value);
     return fbBuilder.offset;
   }
-  int addWeaponsOffset(int offset) {
+  int addWeaponsOffset(int? offset) {
     fbBuilder.addOffset(7, offset);
     return fbBuilder.offset;
   }
-  int addEquippedType(EquipmentTypeId equippedType) {
+  int addEquippedType(EquipmentTypeId? equippedType) {
     fbBuilder.addUint8(8, equippedType?.value);
     return fbBuilder.offset;
   }
-  int addEquippedOffset(int offset) {
+  int addEquippedOffset(int? offset) {
     fbBuilder.addOffset(9, offset);
     return fbBuilder.offset;
   }
-  int addPathOffset(int offset) {
+  int addPathOffset(int? offset) {
     fbBuilder.addOffset(10, offset);
     return fbBuilder.offset;
   }
@@ -265,28 +269,28 @@ class MonsterBuilder {
 }
 
 class MonsterObjectBuilder extends fb.ObjectBuilder {
-  final Vec3ObjectBuilder _pos;
-  final int _mana;
-  final int _hp;
-  final String _name;
-  final List<int> _inventory;
-  final Color _color;
-  final List<WeaponObjectBuilder> _weapons;
-  final EquipmentTypeId _equippedType;
-  final dynamic _equipped;
-  final List<Vec3ObjectBuilder> _path;
+  final Vec3ObjectBuilder? _pos;
+  final int? _mana;
+  final int? _hp;
+  final String? _name;
+  final List<int>? _inventory;
+  final Color? _color;
+  final List<WeaponObjectBuilder>? _weapons;
+  final EquipmentTypeId? _equippedType;
+  final dynamic? _equipped;
+  final List<Vec3ObjectBuilder>? _path;
 
   MonsterObjectBuilder({
-    Vec3ObjectBuilder pos,
-    int mana,
-    int hp,
-    String name,
-    List<int> inventory,
-    Color color,
-    List<WeaponObjectBuilder> weapons,
-    EquipmentTypeId equippedType,
-    dynamic equipped,
-    List<Vec3ObjectBuilder> path,
+    Vec3ObjectBuilder? pos,
+    int? mana,
+    int? hp,
+    String? name,
+    List<int>? inventory,
+    Color? color,
+    List<WeaponObjectBuilder>? weapons,
+    EquipmentTypeId? equippedType,
+    dynamic? equipped,
+    List<Vec3ObjectBuilder>? path,
   })
       : _pos = pos,
         _mana = mana,
@@ -301,50 +305,37 @@ class MonsterObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-    final int nameOffset = fbBuilder.writeString(_name);
-    final int inventoryOffset = _inventory?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(_inventory)
+  int finish(fb.Builder fbBuilder) {
+    final int? nameOffset = fbBuilder.writeString(_name);
+    final int? inventoryOffset = _inventory?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(_inventory!)
         : null;
-    final int weaponsOffset = _weapons?.isNotEmpty == true
-        ? fbBuilder.writeList(_weapons.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
+    final int? weaponsOffset = _weapons?.isNotEmpty == true
+        ? fbBuilder.writeList(_weapons!.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
         : null;
-    final int equippedOffset = _equipped?.getOrCreateOffset(fbBuilder);
-    final int pathOffset = _path?.isNotEmpty == true
-        ? fbBuilder.writeListOfStructs(_path)
+    final int? equippedOffset = _equipped?.getOrCreateOffset(fbBuilder);
+    final int? pathOffset = _path?.isNotEmpty == true
+        ? fbBuilder.writeListOfStructs(_path!)
         : null;
-
     fbBuilder.startTable();
     if (_pos != null) {
-      fbBuilder.addStruct(0, _pos.finish(fbBuilder));
+      fbBuilder.addStruct(0, _pos!.finish(fbBuilder));
     }
     fbBuilder.addInt16(1, _mana);
     fbBuilder.addInt16(2, _hp);
-    if (nameOffset != null) {
-      fbBuilder.addOffset(3, nameOffset);
-    }
-    if (inventoryOffset != null) {
-      fbBuilder.addOffset(5, inventoryOffset);
-    }
+    fbBuilder.addOffset(3, nameOffset);
+    fbBuilder.addOffset(5, inventoryOffset);
     fbBuilder.addInt8(6, _color?.value);
-    if (weaponsOffset != null) {
-      fbBuilder.addOffset(7, weaponsOffset);
-    }
+    fbBuilder.addOffset(7, weaponsOffset);
     fbBuilder.addUint8(8, _equippedType?.value);
-    if (equippedOffset != null) {
-      fbBuilder.addOffset(9, equippedOffset);
-    }
-    if (pathOffset != null) {
-      fbBuilder.addOffset(10, pathOffset);
-    }
+    fbBuilder.addOffset(9, equippedOffset);
+    fbBuilder.addOffset(10, pathOffset);
     return fbBuilder.endTable();
   }
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -362,7 +353,7 @@ class Weapon {
   final fb.BufferContext _bc;
   final int _bcOffset;
 
-  String get name => const fb.StringReader().vTableGet(_bc, _bcOffset, 4, null);
+  String? get name => const fb.StringReader().vTableGetNullable(_bc, _bcOffset, 4);
   int get damage => const fb.Int16Reader().vTableGet(_bc, _bcOffset, 6, 0);
 
   @override
@@ -380,9 +371,7 @@ class _WeaponReader extends fb.TableReader<Weapon> {
 }
 
 class WeaponBuilder {
-  WeaponBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  WeaponBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -390,11 +379,11 @@ class WeaponBuilder {
     fbBuilder.startTable();
   }
 
-  int addNameOffset(int offset) {
+  int addNameOffset(int? offset) {
     fbBuilder.addOffset(0, offset);
     return fbBuilder.offset;
   }
-  int addDamage(int damage) {
+  int addDamage(int? damage) {
     fbBuilder.addInt16(1, damage);
     return fbBuilder.offset;
   }
@@ -405,34 +394,29 @@ class WeaponBuilder {
 }
 
 class WeaponObjectBuilder extends fb.ObjectBuilder {
-  final String _name;
-  final int _damage;
+  final String? _name;
+  final int? _damage;
 
   WeaponObjectBuilder({
-    String name,
-    int damage,
+    String? name,
+    int? damage,
   })
       : _name = name,
         _damage = damage;
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-    final int nameOffset = fbBuilder.writeString(_name);
-
+  int finish(fb.Builder fbBuilder) {
+    final int? nameOffset = fbBuilder.writeString(_name);
     fbBuilder.startTable();
-    if (nameOffset != null) {
-      fbBuilder.addOffset(0, nameOffset);
-    }
+    fbBuilder.addOffset(0, nameOffset);
     fbBuilder.addInt16(1, _damage);
     return fbBuilder.endTable();
   }
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
diff --git a/dart/lib/flat_buffers.dart b/dart/lib/flat_buffers.dart
index 27db49be..74c25943 100644
--- a/dart/lib/flat_buffers.dart
+++ b/dart/lib/flat_buffers.dart
@@ -28,13 +28,17 @@ typedef void StructBuilder();
 class BufferContext {
   final ByteData _buffer;
 
+  ByteData get buffer => _buffer;
+
+  /// Create from a FlatBuffer represented by a list of bytes (uint8).
   factory BufferContext.fromBytes(List<int> byteList) {
     Uint8List uint8List = _asUint8List(byteList);
     ByteData buf = new ByteData.view(uint8List.buffer, uint8List.offsetInBytes);
-    return new BufferContext._(buf);
+    return BufferContext(buf);
   }
 
-  BufferContext._(this._buffer);
+  /// Create from a FlatBuffer represented by ByteData.
+  BufferContext(this._buffer);
 
   int derefObject(int offset) {
     return offset + _getUint32(offset);
@@ -43,31 +47,23 @@ class BufferContext {
   Uint8List _asUint8LIst(int offset, int length) =>
       _buffer.buffer.asUint8List(_buffer.offsetInBytes + offset, length);
 
-  double _getFloat64(int offset) =>
-      _buffer.getFloat64(offset, Endian.little);
+  double _getFloat64(int offset) => _buffer.getFloat64(offset, Endian.little);
 
-  double _getFloat32(int offset) =>
-      _buffer.getFloat32(offset, Endian.little);
+  double _getFloat32(int offset) => _buffer.getFloat32(offset, Endian.little);
 
-  int _getInt64(int offset) =>
-      _buffer.getInt64(offset, Endian.little);
+  int _getInt64(int offset) => _buffer.getInt64(offset, Endian.little);
 
-  int _getInt32(int offset) =>
-      _buffer.getInt32(offset, Endian.little);
+  int _getInt32(int offset) => _buffer.getInt32(offset, Endian.little);
 
-  int _getInt16(int offset) =>
-      _buffer.getInt16(offset, Endian.little);
+  int _getInt16(int offset) => _buffer.getInt16(offset, Endian.little);
 
   int _getInt8(int offset) => _buffer.getInt8(offset);
 
-  int _getUint64(int offset) =>
-      _buffer.getUint64(offset, Endian.little);
+  int _getUint64(int offset) => _buffer.getUint64(offset, Endian.little);
 
-  int _getUint32(int offset) =>
-      _buffer.getUint32(offset, Endian.little);
+  int _getUint32(int offset) => _buffer.getUint32(offset, Endian.little);
 
-  int _getUint16(int offset) =>
-      _buffer.getUint16(offset, Endian.little);
+  int _getUint16(int offset) => _buffer.getUint16(offset, Endian.little);
 
   int _getUint8(int offset) => _buffer.getUint8(offset);
 
@@ -84,7 +80,7 @@ class BufferContext {
 
 /// Class implemented by typed builders generated by flatc.
 abstract class ObjectBuilder {
-  int _firstOffset;
+  int? _firstOffset;
 
   /// Can be used to write the data represented by this builder to the [Builder]
   /// and reuse the offset created in multiple tables.
@@ -94,7 +90,7 @@ abstract class ObjectBuilder {
   /// first call to this method.
   int getOrCreateOffset(Builder fbBuilder) {
     _firstOffset ??= finish(fbBuilder);
-    return _firstOffset;
+    return _firstOffset!;
   }
 
   /// Writes the data in this helper to the [Builder].
@@ -110,8 +106,8 @@ class Builder {
   final int initialSize;
 
   /// The list of existing VTable(s).
-  //final List<_VTable> _vTables = <_VTable>[];
-  final List<int> _vTables = <int>[];
+  final List<int> _vTables = List<int>.filled(16, 0, growable: true)
+    ..length = 0;
 
   ByteData _buf;
 
@@ -125,16 +121,16 @@ class Builder {
   int _tail = 0;
 
   /// The location of the end of the current table, measured in bytes from the
-  /// end of [_buf], or `null` if a table is not currently being built.
-  int _currentTableEndTail;
+  /// end of [_buf].
+  int _currentTableEndTail = 0;
 
-  _VTable _currentVTable;
+  _VTable? _currentVTable;
 
   /// Map containing all strings that have been written so far.  This allows us
   /// to avoid duplicating strings.
   ///
   /// Allocated only if `internStrings` is set to true on the constructor.
-  Map<String, int> _strings;
+  Map<String, int>? _strings;
 
   /// Creates a new FlatBuffers Builder.
   ///
@@ -155,7 +151,7 @@ class Builder {
   /// Add the [field] with the given boolean [value].  The field is not added if
   /// the [value] is equal to [def].  Booleans are stored as 8-bit fields with
   /// `0` for `false` and `1` for `true`.
-  void addBool(int field, bool value, [bool def]) {
+  void addBool(int field, bool? value, [bool? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofUint8, 1);
@@ -166,7 +162,7 @@ class Builder {
 
   /// Add the [field] with the given 32-bit signed integer [value].  The field is
   /// not added if the [value] is equal to [def].
-  void addInt32(int field, int value, [int def]) {
+  void addInt32(int field, int? value, [int? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofInt32, 1);
@@ -177,7 +173,7 @@ class Builder {
 
   /// Add the [field] with the given 32-bit signed integer [value].  The field is
   /// not added if the [value] is equal to [def].
-  void addInt16(int field, int value, [int def]) {
+  void addInt16(int field, int? value, [int? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofInt16, 1);
@@ -188,7 +184,7 @@ class Builder {
 
   /// Add the [field] with the given 8-bit signed integer [value].  The field is
   /// not added if the [value] is equal to [def].
-  void addInt8(int field, int value, [int def]) {
+  void addInt8(int field, int? value, [int? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofInt8, 1);
@@ -200,11 +196,11 @@ class Builder {
   void addStruct(int field, int offset) {
     _ensureCurrentVTable();
     _trackField(field);
-    _currentVTable.addField(field, offset);
+    _currentVTable!.addField(field, offset);
   }
 
   /// Add the [field] referencing an object with the given [offset].
-  void addOffset(int field, int offset) {
+  void addOffset(int field, int? offset) {
     _ensureCurrentVTable();
     if (offset != null) {
       _prepare(_sizeofUint32, 1);
@@ -215,7 +211,7 @@ class Builder {
 
   /// Add the [field] with the given 32-bit unsigned integer [value].  The field
   /// is not added if the [value] is equal to [def].
-  void addUint32(int field, int value, [int def]) {
+  void addUint32(int field, int? value, [int? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofUint32, 1);
@@ -226,7 +222,7 @@ class Builder {
 
   /// Add the [field] with the given 32-bit unsigned integer [value].  The field
   /// is not added if the [value] is equal to [def].
-  void addUint16(int field, int value, [int def]) {
+  void addUint16(int field, int? value, [int? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofUint16, 1);
@@ -237,7 +233,7 @@ class Builder {
 
   /// Add the [field] with the given 8-bit unsigned integer [value].  The field
   /// is not added if the [value] is equal to [def].
-  void addUint8(int field, int value, [int def]) {
+  void addUint8(int field, int? value, [int? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofUint8, 1);
@@ -248,7 +244,7 @@ class Builder {
 
   /// Add the [field] with the given 32-bit float [value].  The field
   /// is not added if the [value] is equal to [def].
-  void addFloat32(int field, double value, [double def]) {
+  void addFloat32(int field, double? value, [double? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofFloat32, 1);
@@ -259,7 +255,7 @@ class Builder {
 
   /// Add the [field] with the given 64-bit double [value].  The field
   /// is not added if the [value] is equal to [def].
-  void addFloat64(int field, double value, [double def]) {
+  void addFloat64(int field, double? value, [double? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofFloat64, 1);
@@ -270,7 +266,7 @@ class Builder {
 
   /// Add the [field] with the given 64-bit unsigned integer [value].  The field
   /// is not added if the [value] is equal to [def].
-  void addUint64(int field, int value, [double def]) {
+  void addUint64(int field, int? value, [double? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofUint64, 1);
@@ -281,7 +277,7 @@ class Builder {
 
   /// Add the [field] with the given 64-bit unsigned integer [value].  The field
   /// is not added if the [value] is equal to [def].
-  void addInt64(int field, int value, [double def]) {
+  void addInt64(int field, int? value, [double? def]) {
     _ensureCurrentVTable();
     if (value != null && value != def) {
       _prepare(_sizeofInt64, 1);
@@ -299,11 +295,12 @@ class Builder {
     _prepare(_sizeofInt32, 1);
     int tableTail = _tail;
     // Prepare the size of the current table.
-    _currentVTable.tableSize = tableTail - _currentTableEndTail;
+    final currentVTable = _currentVTable!;
+    currentVTable.tableSize = tableTail - _currentTableEndTail;
     // Prepare the VTable to use for the current table.
-    int vTableTail;
+    int? vTableTail;
     {
-      _currentVTable.computeFieldOffsets(tableTail);
+      currentVTable.computeFieldOffsets(tableTail);
       // Try to find an existing compatible VTable.
       // Search backward - more likely to have recently used one
       for (int i = _vTables.length - 1; i >= 0; i--) {
@@ -311,19 +308,19 @@ class Builder {
         final int vt2Start = _buf.lengthInBytes - vt2Offset;
         final int vt2Size = _buf.getUint16(vt2Start, Endian.little);
 
-        if (_currentVTable._vTableSize == vt2Size &&
-            _currentVTable._offsetsMatch(vt2Start, _buf)) {
+        if (currentVTable._vTableSize == vt2Size &&
+            currentVTable._offsetsMatch(vt2Start, _buf)) {
           vTableTail = vt2Offset;
           break;
         }
       }
       // Write a new VTable.
       if (vTableTail == null) {
-        _prepare(_sizeofUint16, _currentVTable.numOfUint16);
+        _prepare(_sizeofUint16, _currentVTable!.numOfUint16);
         vTableTail = _tail;
-        _currentVTable.tail = vTableTail;
-        _currentVTable.output(_buf, _buf.lengthInBytes - _tail);
-        _vTables.add(_currentVTable.tail);
+        currentVTable.tail = vTableTail;
+        currentVTable.output(_buf, _buf.lengthInBytes - _tail);
+        _vTables.add(currentVTable.tail);
       }
     }
     // Set the VTable offset.
@@ -346,7 +343,7 @@ class Builder {
   /// written object.  If [fileIdentifier] is specified (and not `null`), it is
   /// interpreted as a 4-byte Latin-1 encoded string that should be placed at
   /// bytes 4-7 of the file.
-  Uint8List finish(int offset, [String fileIdentifier]) {
+  Uint8List finish(int offset, [String? fileIdentifier]) {
     _prepare(max(_sizeofUint32, _maxAlign), fileIdentifier == null ? 1 : 2);
     final finishedSize = size();
     _setUint32AtTail(_buf, finishedSize, finishedSize - offset);
@@ -444,7 +441,7 @@ class Builder {
     _maxAlign = 1;
     _tail = 0;
     _currentVTable = null;
-    _vTables.clear();
+    _vTables.length = 0;
     if (_strings != null) {
       _strings = new Map<String, int>();
     }
@@ -613,7 +610,7 @@ class Builder {
 
   /// Write the given list of bools as unsigend 8-bit integer [values].
   int writeListBool(List<bool> values) {
-    return writeListUint8(values?.map((b) => b ? 1 : 0)?.toList());
+    return writeListUint8(values.map((b) => b ? 1 : 0).toList());
   }
 
   /// Write the given list of signed 8-bit integer [values].
@@ -648,11 +645,11 @@ class Builder {
 
   /// Write the given string [value] and return its offset, or `null` if
   /// the [value] is `null`.
-  int writeString(String value) {
+  int? writeString(String? value) {
     _ensureNoVTable();
     if (value != null) {
       if (_strings != null) {
-        return _strings.putIfAbsent(value, () => _writeString(value));
+        return _strings!.putIfAbsent(value, () => _writeString(value));
       } else {
         return _writeString(value);
       }
@@ -732,7 +729,7 @@ class Builder {
 
   /// Record the offset of the given [field].
   void _trackField(int field) {
-    _currentVTable.addField(field, _tail);
+    _currentVTable!.addField(field, _tail);
   }
 
   static void _setFloat64AtTail(ByteData _buf, int tail, double x) {
@@ -848,6 +845,7 @@ class Float32Reader extends Reader<double> {
 
 class Int64Reader extends Reader<int> {
   const Int64Reader() : super();
+
   @override
   int get size => _sizeofInt64;
 
@@ -915,19 +913,23 @@ abstract class Reader<T> {
   T read(BufferContext bc, int offset);
 
   /// Read the value of the given [field] in the given [object].
-  T vTableGet(BufferContext object, int offset, int field, [T defaultValue]) {
+  T vTableGet(BufferContext object, int offset, int field, T defaultValue) {
+    int fieldOffset = _vTableFieldOffset(object, offset, field);
+    return fieldOffset == 0 ? defaultValue : read(object, offset + fieldOffset);
+  }
+
+  /// Read the value of the given [field] in the given [object].
+  T? vTableGetNullable(BufferContext object, int offset, int field) {
+    int fieldOffset = _vTableFieldOffset(object, offset, field);
+    return fieldOffset == 0 ? null : read(object, offset + fieldOffset);
+  }
+
+  int _vTableFieldOffset(BufferContext object, int offset, int field) {
     int vTableSOffset = object._getInt32(offset);
     int vTableOffset = offset - vTableSOffset;
     int vTableSize = object._getUint16(vTableOffset);
-    int vTableFieldOffset = field;
-    if (vTableFieldOffset < vTableSize) {
-      int fieldOffsetInObject =
-          object._getUint16(vTableOffset + vTableFieldOffset);
-      if (fieldOffsetInObject != 0) {
-        return read(object, offset + fieldOffsetInObject);
-      }
-    }
-    return defaultValue;
+    if (field >= vTableSize) return 0;
+    return object._getUint16(vTableOffset + field);
   }
 }
 
@@ -1101,20 +1103,20 @@ class _FbFloat32List extends _FbList<double> {
 class _FbGenericList<E> extends _FbList<E> {
   final Reader<E> elementReader;
 
-  List<E> _items;
+  List<E?>? _items;
 
   _FbGenericList(this.elementReader, BufferContext bp, int offset)
       : super(bp, offset);
 
   @override
   E operator [](int i) {
-    _items ??= new List<E>(length);
-    E item = _items[i];
+    _items ??= List<E?>.filled(length, null);
+    E? item = _items![i];
     if (item == null) {
       item = elementReader.read(bc, offset + 4 + elementReader.size * i);
-      _items[i] = item;
+      _items![i] = item;
     }
-    return item;
+    return item!;
   }
 }
 
@@ -1122,14 +1124,14 @@ class _FbGenericList<E> extends _FbList<E> {
 abstract class _FbList<E> extends Object with ListMixin<E> implements List<E> {
   final BufferContext bc;
   final int offset;
-  int _length;
+  int? _length;
 
   _FbList(this.bc, this.offset);
 
   @override
   int get length {
     _length ??= bc._getUint32(offset);
-    return _length;
+    return _length!;
   }
 
   @override
@@ -1185,15 +1187,15 @@ class _FbBoolList extends _FbList<bool> {
 class _VTable {
   static const int _metadataLength = 4;
 
-  final List<int> fieldTails = <int>[];
-  final List<int> fieldOffsets = <int>[];
+  final fieldTails = <int?>[];
+  final fieldOffsets = <int>[];
 
   /// The size of the table that uses this VTable.
-  int tableSize;
+  int tableSize = 0;
 
-  /// The tail of this VTable.  It is used to share the same VTable between
+  /// The tail of this VTable. It is used to share the same VTable between
   /// multiple tables of identical structure.
-  int tail;
+  int tail = 0;
 
   int get _vTableSize => numOfUint16 * _sizeofUint16;
 
@@ -1209,8 +1211,7 @@ class _VTable {
   bool _offsetsMatch(int vt2Start, ByteData buf) {
     for (int i = 0; i < fieldOffsets.length; i++) {
       if (fieldOffsets[i] !=
-          buf.getUint16(
-              vt2Start + _metadataLength + (2 * i), Endian.little)) {
+          buf.getUint16(vt2Start + _metadataLength + (2 * i), Endian.little)) {
         return false;
       }
     }
@@ -1220,7 +1221,7 @@ class _VTable {
   /// Fill the [fieldOffsets] field.
   void computeFieldOffsets(int tableTail) {
     assert(fieldOffsets.isEmpty);
-    for (int fieldTail in fieldTails) {
+    for (int? fieldTail in fieldTails) {
       int fieldOffset = fieldTail == null ? 0 : tableTail - fieldTail;
       fieldOffsets.add(fieldOffset);
     }
diff --git a/dart/lib/src/builder.dart b/dart/lib/src/builder.dart
index 5ce46dcb..27c0184a 100644
--- a/dart/lib/src/builder.dart
+++ b/dart/lib/src/builder.dart
@@ -6,37 +6,26 @@ import 'types.dart';
 /// The main builder class for creation of a FlexBuffer.
 class Builder {
   ByteData _buffer;
-  List<_StackValue> _stack;
-  List<_StackPointer> _stackPointers;
-  int _offset;
-  bool _finished;
-  Map<String, _StackValue> _stringCache;
-  Map<String, _StackValue> _keyCache;
-  Map<_KeysHash, _StackValue> _keyVectorCache;
-  Map<int, _StackValue> _indirectIntCache;
-  Map<double, _StackValue> _indirectDoubleCache;
+  List<_StackValue> _stack = [];
+  List<_StackPointer> _stackPointers = [];
+  int _offset = 0;
+  bool _finished = false;
+  Map<String, _StackValue> _stringCache = {};
+  Map<String, _StackValue> _keyCache = {};
+  Map<_KeysHash, _StackValue> _keyVectorCache = {};
+  Map<int, _StackValue> _indirectIntCache = {};
+  Map<double, _StackValue> _indirectDoubleCache = {};
 
   /// Instantiate the builder if you intent to gradually build up the buffer by calling
   /// add... methods and calling [finish] to receive the the resulting byte array.
   ///
   /// The default size of internal buffer is set to 2048. Provide a different value in order to avoid buffer copies.
-  Builder({int size = 2048}) {
-    _buffer = ByteData(size);
-    _stack = [];
-    _stackPointers = [];
-    _offset = 0;
-    _finished = false;
-    _stringCache = {};
-    _keyCache = {};
-    _keyVectorCache = {};
-    _indirectIntCache = {};
-    _indirectDoubleCache = {};
-  }
+  Builder({int size = 2048}) : _buffer = ByteData(size) {}
 
   /// Use this method in order to turn an object into a FlexBuffer directly.
   ///
   /// Use the manual instantiation of the [Builder] and gradual addition of values, if performance is more important than convenience.
-  static ByteBuffer buildFromObject(Object value) {
+  static ByteBuffer buildFromObject(Object? value) {
     final builder = Builder();
     builder._add(value);
     final buffer = builder.finish();
@@ -45,7 +34,7 @@ class Builder {
     return byteData.buffer;
   }
 
-  void _add(Object value) {
+  void _add(Object? value) {
     if (value == null) {
       addNull();
     } else if (value is bool) {
@@ -106,7 +95,7 @@ class Builder {
   void addString(String value) {
     _integrityCheckOnValueAddition();
     if (_stringCache.containsKey(value)) {
-      _stack.add(_stringCache[value]);
+      _stack.add(_stringCache[value]!);
       return;
     }
     final utf8String = utf8.encode(value);
@@ -118,7 +107,8 @@ class Builder {
     final newOffset = _newOffset(length + 1);
     _pushBuffer(utf8String);
     _offset = newOffset;
-    final stackValue = _StackValue.WithOffset(stringOffset, ValueType.String, bitWidth);
+    final stackValue =
+        _StackValue.WithOffset(stringOffset, ValueType.String, bitWidth);
     _stack.add(stackValue);
     _stringCache[value] = stackValue;
   }
@@ -129,7 +119,7 @@ class Builder {
   void addKey(String value) {
     _integrityCheckOnKeyAddition();
     if (_keyCache.containsKey(value)) {
-      _stack.add(_keyCache[value]);
+      _stack.add(_keyCache[value]!);
       return;
     }
     final utf8String = utf8.encode(value);
@@ -138,7 +128,8 @@ class Builder {
     final newOffset = _newOffset(length + 1);
     _pushBuffer(utf8String);
     _offset = newOffset;
-    final stackValue = _StackValue.WithOffset(keyOffset, ValueType.Key, BitWidth.width8);
+    final stackValue =
+        _StackValue.WithOffset(keyOffset, ValueType.Key, BitWidth.width8);
     _stack.add(stackValue);
     _keyCache[value] = stackValue;
   }
@@ -156,7 +147,8 @@ class Builder {
     final newOffset = _newOffset(length);
     _pushBuffer(value.asUint8List());
     _offset = newOffset;
-    final stackValue = _StackValue.WithOffset(blobOffset, ValueType.Blob, bitWidth);
+    final stackValue =
+        _StackValue.WithOffset(blobOffset, ValueType.Blob, bitWidth);
     _stack.add(stackValue);
   }
 
@@ -169,7 +161,7 @@ class Builder {
   void addIntIndirectly(int value, {bool cache = false}) {
     _integrityCheckOnValueAddition();
     if (_indirectIntCache.containsKey(value)) {
-      _stack.add(_indirectIntCache[value]);
+      _stack.add(_indirectIntCache[value]!);
       return;
     }
     final stackValue = _StackValue.WithInt(value);
@@ -177,7 +169,8 @@ class Builder {
     final newOffset = _newOffset(byteWidth);
     final valueOffset = _offset;
     _pushBuffer(stackValue.asU8List(stackValue.width));
-    final stackOffset = _StackValue.WithOffset(valueOffset, ValueType.IndirectInt, stackValue.width);
+    final stackOffset = _StackValue.WithOffset(
+        valueOffset, ValueType.IndirectInt, stackValue.width);
     _stack.add(stackOffset);
     _offset = newOffset;
     if (cache) {
@@ -193,7 +186,7 @@ class Builder {
   void addDoubleIndirectly(double value, {bool cache = false}) {
     _integrityCheckOnValueAddition();
     if (cache && _indirectDoubleCache.containsKey(value)) {
-      _stack.add(_indirectDoubleCache[value]);
+      _stack.add(_indirectDoubleCache[value]!);
       return;
     }
     final stackValue = _StackValue.WithDouble(value);
@@ -201,7 +194,8 @@ class Builder {
     final newOffset = _newOffset(byteWidth);
     final valueOffset = _offset;
     _pushBuffer(stackValue.asU8List(stackValue.width));
-    final stackOffset = _StackValue.WithOffset(valueOffset, ValueType.IndirectFloat, stackValue.width);
+    final stackOffset = _StackValue.WithOffset(
+        valueOffset, ValueType.IndirectFloat, stackValue.width);
     _stack.add(stackOffset);
     _offset = newOffset;
     if (cache) {
@@ -258,8 +252,10 @@ class Builder {
     tmp._offset = _offset;
     tmp._stack = List.from(_stack);
     tmp._stackPointers = List.from(_stackPointers);
-    tmp._buffer.buffer.asUint8List().setAll(0, _buffer.buffer.asUint8List(0, _offset));
-    for (var i = 0; i < tmp._stackPointers.length; i++){
+    tmp._buffer.buffer
+        .asUint8List()
+        .setAll(0, _buffer.buffer.asUint8List(0, _offset));
+    for (var i = 0; i < tmp._stackPointers.length; i++) {
       tmp.end();
     }
     final buffer = tmp.finish();
@@ -267,14 +263,15 @@ class Builder {
     bd.buffer.asUint8List().setAll(0, buffer);
     return bd.buffer;
   }
-  
+
   void _integrityCheckOnValueAddition() {
     if (_finished) {
       throw StateError('Adding values after finish is prohibited');
     }
     if (_stackPointers.isNotEmpty && _stackPointers.last.isVector == false) {
       if (_stack.last.type != ValueType.Key) {
-        throw StateError('Adding value to a map before adding a key is prohibited');
+        throw StateError(
+            'Adding value to a map before adding a key is prohibited');
       }
     }
   }
@@ -290,7 +287,8 @@ class Builder {
 
   void _finish() {
     if (_stack.length != 1) {
-      throw StateError('Stack has to be exactly 1, but is ${_stack.length}. You have to end all started vectors and maps, before calling [finish]');
+      throw StateError(
+          'Stack has to be exactly 1, but is ${_stack.length}. You have to end all started vectors and maps, before calling [finish]');
     }
     final value = _stack[0];
     final byteWidth = _align(value.elementWidth(_offset, 0));
@@ -299,8 +297,9 @@ class Builder {
     _writeUInt(byteWidth, 1);
     _finished = true;
   }
-  
-  _StackValue _createVector(int start, int vecLength, int step, [_StackValue keys]) {
+
+  _StackValue _createVector(int start, int vecLength, int step,
+      [_StackValue? keys]) {
     var bitWidth = BitWidthUtil.uwidth(vecLength);
     var prefixElements = 1;
     if (keys != null) {
@@ -327,7 +326,9 @@ class Builder {
       }
     }
     final byteWidth = _align(bitWidth);
-    final fix = typed & ValueTypeUtils.isNumber(vectorType) && vecLength >= 2 && vecLength <= 4;
+    final fix = typed & ValueTypeUtils.isNumber(vectorType) &&
+        vecLength >= 2 &&
+        vecLength <= 4;
     if (keys != null) {
       _writeStackValue(keys, byteWidth);
       _writeUInt(1 << keys.width.index, byteWidth);
@@ -348,7 +349,8 @@ class Builder {
       return _StackValue.WithOffset(vecOffset, ValueType.Map, bitWidth);
     }
     if (typed) {
-      final vType = ValueTypeUtils.toTypedVector(vectorType, fix ? vecLength : 0);
+      final vType =
+          ValueTypeUtils.toTypedVector(vectorType, fix ? vecLength : 0);
       return _StackValue.WithOffset(vecOffset, vType, bitWidth);
     }
     return _StackValue.WithOffset(vecOffset, ValueType.Vector, bitWidth);
@@ -363,12 +365,13 @@ class Builder {
 
   void _sortKeysAndEndMap(_StackPointer pointer) {
     if (((_stack.length - pointer.stackPosition) & 1) == 1) {
-      throw StateError('The stack needs to hold key value pairs (even number of elements). Check if you combined [addKey] with add... method calls properly.');
+      throw StateError(
+          'The stack needs to hold key value pairs (even number of elements). Check if you combined [addKey] with add... method calls properly.');
     }
 
     var sorted = true;
     for (var i = pointer.stackPosition; i < _stack.length - 2; i += 2) {
-      if (_shouldFlip(_stack[i], _stack[i+2])) {
+      if (_shouldFlip(_stack[i], _stack[i + 2])) {
         sorted = false;
         break;
       }
@@ -394,12 +397,12 @@ class Builder {
     }
     _endMap(pointer);
   }
-  
+
   void _endMap(_StackPointer pointer) {
     final vecLength = (_stack.length - pointer.stackPosition) >> 1;
     final offsets = <int>[];
     for (var i = pointer.stackPosition; i < _stack.length; i += 2) {
-      offsets.add(_stack[i].offset);
+      offsets.add(_stack[i].offset!);
     }
     final keysHash = _KeysHash(offsets);
     var keysStackValue;
@@ -409,21 +412,23 @@ class Builder {
       keysStackValue = _createVector(pointer.stackPosition, vecLength, 2);
       _keyVectorCache[keysHash] = keysStackValue;
     }
-    final vec = _createVector(pointer.stackPosition + 1, vecLength, 2, keysStackValue);
+    final vec =
+        _createVector(pointer.stackPosition + 1, vecLength, 2, keysStackValue);
     _stack.removeRange(pointer.stackPosition, _stack.length);
     _stack.add(vec);
   }
 
   bool _shouldFlip(_StackValue v1, _StackValue v2) {
     if (v1.type != ValueType.Key || v2.type != ValueType.Key) {
-      throw StateError('Stack values are not keys $v1 | $v2. Check if you combined [addKey] with add... method calls properly.');
+      throw StateError(
+          'Stack values are not keys $v1 | $v2. Check if you combined [addKey] with add... method calls properly.');
     }
 
     var c1, c2;
     var index = 0;
     do {
-      c1 = _buffer.getUint8(v1.offset + index);
-      c2 = _buffer.getUint8(v2.offset + index);
+      c1 = _buffer.getUint8(v1.offset! + index);
+      c2 = _buffer.getUint8(v2.offset! + index);
       if (c2 < c1) return true;
       if (c1 < c2) return false;
       index += 1;
@@ -440,11 +445,12 @@ class Builder {
   void _writeStackValue(_StackValue value, int byteWidth) {
     final newOffset = _newOffset(byteWidth);
     if (value.isOffset) {
-      final relativeOffset = _offset - value.offset;
+      final relativeOffset = _offset - value.offset!;
       if (byteWidth == 8 || relativeOffset < (1 << (byteWidth * 8))) {
         _writeUInt(relativeOffset, byteWidth);
       } else {
-        throw StateError('Unexpected size $byteWidth. This might be a bug. Please create an issue https://github.com/google/flatbuffers/issues/new');
+        throw StateError(
+            'Unexpected size $byteWidth. This might be a bug. Please create an issue https://github.com/google/flatbuffers/issues/new');
       }
     } else {
       _pushBuffer(value.asU8List(BitWidthUtil.fromByteWidth(byteWidth)));
@@ -467,16 +473,13 @@ class Builder {
     }
     if (prevSize < size) {
       final newBuf = ByteData(size);
-      newBuf.buffer
-          .asUint8List()
-          .setAll(0, _buffer.buffer.asUint8List());
+      newBuf.buffer.asUint8List().setAll(0, _buffer.buffer.asUint8List());
     }
     return newOffset;
   }
 
   void _pushInt(int value, BitWidth width) {
     switch (width) {
-
       case BitWidth.width8:
         _buffer.setInt8(_offset, value);
         break;
@@ -494,7 +497,6 @@ class Builder {
 
   void _pushUInt(int value, BitWidth width) {
     switch (width) {
-
       case BitWidth.width8:
         _buffer.setUint8(_offset, value);
         break;
@@ -516,37 +518,39 @@ class Builder {
 }
 
 class _StackValue {
-  Object _value;
-  int _offset;
+  late Object _value;
+  int? _offset;
   ValueType _type;
   BitWidth _width;
-  _StackValue.WithNull() {
-    _type = ValueType.Null;
-    _width = BitWidth.width8;
-  }
-  _StackValue.WithInt(int value) {
-    _type = value != null ? ValueType.Int : ValueType.Null;
-    _width = BitWidthUtil.width(value);
-    _value = value;
-  }
-  _StackValue.WithBool(bool value) {
-    _type = value != null ? ValueType.Bool : ValueType.Null;
-    _width = BitWidth.width8;
-    _value = value;
-  }
-  _StackValue.WithDouble(double value) {
-    _type = value != null ? ValueType.Float : ValueType.Null;
-    _width = BitWidthUtil.width(value);
-    _value = value;
-  }
-  _StackValue.WithOffset(int value, ValueType type, BitWidth width) {
-    _offset = value;
-    _type = type;
-    _width = width;
-  }
+
+  _StackValue.WithNull()
+      : _type = ValueType.Null,
+        _width = BitWidth.width8 {}
+
+  _StackValue.WithInt(int value)
+      : _type = ValueType.Int,
+        _width = BitWidthUtil.width(value),
+        _value = value {}
+
+  _StackValue.WithBool(bool value)
+      : _type = ValueType.Bool,
+        _width = BitWidth.width8,
+        _value = value {}
+
+  _StackValue.WithDouble(double value)
+      : _type = ValueType.Float,
+        _width = BitWidthUtil.width(value),
+        _value = value {}
+
+  _StackValue.WithOffset(int value, ValueType type, BitWidth width)
+      : _offset = value,
+        _type = type,
+        _width = width {}
 
   BitWidth storedWidth({BitWidth width = BitWidth.width8}) {
-    return ValueTypeUtils.isInline(_type) ? BitWidthUtil.max(_width, width) : _width;
+    return ValueTypeUtils.isInline(_type)
+        ? BitWidthUtil.max(_width, width)
+        : _width;
   }
 
   int storedPackedType({BitWidth width = BitWidth.width8}) {
@@ -555,16 +559,18 @@ class _StackValue {
 
   BitWidth elementWidth(int size, int index) {
     if (ValueTypeUtils.isInline(_type)) return _width;
-    for(var i = 0; i < 4; i++) {
+    final offset = offsetLoc - _offset!;
+    for (var i = 0; i < 4; i++) {
       final width = 1 << i;
-      final offsetLoc = size + BitWidthUtil.paddingSize(size, width) + index * width;
-      final offset = offsetLoc - _offset;
+      final offsetLoc =
+          size + BitWidthUtil.paddingSize(size, width) + index * width;
       final bitWidth = BitWidthUtil.uwidth(offset);
       if (1 << bitWidth.index == width) {
         return bitWidth;
       }
     }
-    throw StateError('Element is of unknown. Size: $size at index: $index. This might be a bug. Please create an issue https://github.com/google/flatbuffers/issues/new');
+    throw StateError(
+        'Element is of unknown. Size: $size at index: $index. This might be a bug. Please create an issue https://github.com/google/flatbuffers/issues/new');
   }
 
   List<int> asU8List(BitWidth width) {
@@ -572,30 +578,30 @@ class _StackValue {
       if (_type == ValueType.Float) {
         if (width == BitWidth.width32) {
           final result = ByteData(4);
-          result.setFloat32(0, _value, Endian.little);
+          result.setFloat32(0, _value as double, Endian.little);
           return result.buffer.asUint8List();
         } else {
           final result = ByteData(8);
-          result.setFloat64(0, _value, Endian.little);
+          result.setFloat64(0, _value as double, Endian.little);
           return result.buffer.asUint8List();
         }
       } else {
-        switch(width) {
+        switch (width) {
           case BitWidth.width8:
             final result = ByteData(1);
-            result.setInt8(0, _value);
+            result.setInt8(0, _value as int);
             return result.buffer.asUint8List();
           case BitWidth.width16:
             final result = ByteData(2);
-            result.setInt16(0, _value, Endian.little);
+            result.setInt16(0, _value as int, Endian.little);
             return result.buffer.asUint8List();
           case BitWidth.width32:
             final result = ByteData(4);
-            result.setInt32(0, _value, Endian.little);
+            result.setInt32(0, _value as int, Endian.little);
             return result.buffer.asUint8List();
           case BitWidth.width64:
             final result = ByteData(8);
-            result.setInt64(0, _value, Endian.little);
+            result.setInt64(0, _value as int, Endian.little);
             return result.buffer.asUint8List();
         }
       }
@@ -607,11 +613,12 @@ class _StackValue {
     }
     if (_type == ValueType.Bool) {
       final result = ByteData(1);
-      result.setInt8(0, _value ? 1 : 0);
+      result.setInt8(0, _value as bool ? 1 : 0);
       return result.buffer.asUint8List();
     }
 
-    throw StateError('Unexpected type: $_type. This might be a bug. Please create an issue https://github.com/google/flatbuffers/issues/new');
+    throw StateError(
+        'Unexpected type: $_type. This might be a bug. Please create an issue https://github.com/google/flatbuffers/issues/new');
   }
 
   ValueType get type {
@@ -625,7 +632,8 @@ class _StackValue {
   bool get isOffset {
     return !ValueTypeUtils.isInline(_type);
   }
-  int get offset => _offset;
+
+  int? get offset => _offset;
 
   bool get isFloat32 {
     return _type == ValueType.Float && _width == BitWidth.width32;
diff --git a/dart/lib/src/reference.dart b/dart/lib/src/reference.dart
index 3954f068..c2956e30 100644
--- a/dart/lib/src/reference.dart
+++ b/dart/lib/src/reference.dart
@@ -11,14 +11,15 @@ class Reference {
   final int _offset;
   final BitWidth _parentWidth;
   final String _path;
-  int _byteWidth;
-  ValueType _valueType;
-  int _length;
+  final int _byteWidth;
+  final ValueType _valueType;
+  int? _length;
 
-  Reference._(this._buffer, this._offset, this._parentWidth, int packedType, this._path) {
-    _byteWidth = 1 << (packedType & 3);
-    _valueType = ValueTypeUtils.fromInt(packedType >> 2);
-  }
+  Reference._(
+      this._buffer, this._offset, this._parentWidth, int packedType, this._path,
+      [int? byteWidth, ValueType? valueType])
+      : _byteWidth = byteWidth ?? 1 << (packedType & 3),
+        _valueType = valueType ?? ValueTypeUtils.fromInt(packedType >> 2) {}
 
   /// Use this method to access the root value of a FlexBuffer.
   static Reference fromBuffer(ByteBuffer buffer) {
@@ -30,31 +31,44 @@ class Reference {
     final byteWidth = byteData.getUint8(len - 1);
     final packedType = byteData.getUint8(len - 2);
     final offset = len - byteWidth - 2;
-    return Reference._(ByteData.view(buffer), offset, BitWidthUtil.fromByteWidth(byteWidth), packedType, "/");
+    return Reference._(ByteData.view(buffer), offset,
+        BitWidthUtil.fromByteWidth(byteWidth), packedType, "/");
   }
 
   /// Returns true if the underlying value is null.
   bool get isNull => _valueType == ValueType.Null;
+
   /// Returns true if the underlying value can be represented as [num].
-  bool get isNum => ValueTypeUtils.isNumber(_valueType) || ValueTypeUtils.isIndirectNumber(_valueType);
+  bool get isNum =>
+      ValueTypeUtils.isNumber(_valueType) ||
+      ValueTypeUtils.isIndirectNumber(_valueType);
+
   /// Returns true if the underlying value was encoded as a float (direct or indirect).
-  bool get isDouble => _valueType == ValueType.Float || _valueType == ValueType.IndirectFloat;
+  bool get isDouble =>
+      _valueType == ValueType.Float || _valueType == ValueType.IndirectFloat;
+
   /// Returns true if the underlying value was encoded as an int or uint (direct or indirect).
   bool get isInt => isNum && !isDouble;
+
   /// Returns true if the underlying value was encoded as a string or a key.
-  bool get isString => _valueType == ValueType.String || _valueType == ValueType.Key;
+  bool get isString =>
+      _valueType == ValueType.String || _valueType == ValueType.Key;
+
   /// Returns true if the underlying value was encoded as a bool.
   bool get isBool => _valueType == ValueType.Bool;
+
   /// Returns true if the underlying value was encoded as a blob.
   bool get isBlob => _valueType == ValueType.Blob;
+
   /// Returns true if the underlying value points to a vector.
   bool get isVector => ValueTypeUtils.isAVector(_valueType);
+
   /// Returns true if the underlying value points to a map.
   bool get isMap => _valueType == ValueType.Map;
 
   /// If this [isBool], returns the bool value. Otherwise, returns null.
-  bool get boolValue {
-    if(_valueType == ValueType.Bool) {
+  bool? get boolValue {
+    if (_valueType == ValueType.Bool) {
       return _readInt(_offset, _parentWidth) != 0;
     }
     return null;
@@ -63,7 +77,7 @@ class Reference {
   /// Returns an [int], if the underlying value can be represented as an int.
   ///
   /// Otherwise returns [null].
-  int get intValue {
+  int? get intValue {
     if (_valueType == ValueType.Int) {
       return _readInt(_offset, _parentWidth);
     }
@@ -82,7 +96,7 @@ class Reference {
   /// Returns [double], if the underlying value [isDouble].
   ///
   /// Otherwise returns [null].
-  double get doubleValue {
+  double? get doubleValue {
     if (_valueType == ValueType.Float) {
       return _readFloat(_offset, _parentWidth);
     }
@@ -95,12 +109,12 @@ class Reference {
   /// Returns [num], if the underlying value is numeric, be it int uint, or float (direct or indirect).
   ///
   /// Otherwise returns [null].
-  num get numValue => doubleValue ?? intValue;
+  num? get numValue => doubleValue ?? intValue;
 
   /// Returns [String] value or null otherwise.
-  /// 
-  /// This method performers a utf8 decoding, as FlexBuffers format stores strings in utf8 encoding. 
-  String get stringValue {
+  ///
+  /// This method performers a utf8 decoding, as FlexBuffers format stores strings in utf8 encoding.
+  String? get stringValue {
     if (_valueType == ValueType.String || _valueType == ValueType.Key) {
       return utf8.decode(_buffer.buffer.asUint8List(_indirect, length));
     }
@@ -108,7 +122,7 @@ class Reference {
   }
 
   /// Returns [Uint8List] value or null otherwise.
-  Uint8List get blobValue {
+  Uint8List? get blobValue {
     if (_valueType == ValueType.Blob) {
       return _buffer.buffer.asUint8List(_indirect, length);
     }
@@ -122,22 +136,31 @@ class Reference {
   Reference operator [](Object key) {
     if (key is int && ValueTypeUtils.isAVector(_valueType)) {
       final index = key;
-      if(index >= length || index < 0) {
-        throw ArgumentError('Key: [$key] is not applicable on: $_path of: $_valueType length: $length');
+      if (index >= length || index < 0) {
+        throw ArgumentError(
+            'Key: [$key] is not applicable on: $_path of: $_valueType length: $length');
       }
       final elementOffset = _indirect + index * _byteWidth;
-      final reference = Reference._(_buffer, elementOffset, BitWidthUtil.fromByteWidth(_byteWidth), 0, "$_path[$index]");
-      reference._byteWidth = 1;
+      int packedType = 0;
+      int? byteWidth;
+      ValueType? valueType;
       if (ValueTypeUtils.isTypedVector(_valueType)) {
-        reference._valueType = ValueTypeUtils.typedVectorElementType(_valueType);
-        return reference;
-      }
-      if(ValueTypeUtils.isFixedTypedVector(_valueType)) {
-        reference._valueType = ValueTypeUtils.fixedTypedVectorElementType(_valueType);
-        return reference;
+        byteWidth = 1;
+        valueType = ValueTypeUtils.typedVectorElementType(_valueType);
+      } else if (ValueTypeUtils.isFixedTypedVector(_valueType)) {
+        byteWidth = 1;
+        valueType = ValueTypeUtils.fixedTypedVectorElementType(_valueType);
+      } else {
+        packedType = _buffer.getUint8(_indirect + length * _byteWidth + index);
       }
-      final packedType = _buffer.getUint8(_indirect + length * _byteWidth + index);
-      return Reference._(_buffer, elementOffset, BitWidthUtil.fromByteWidth(_byteWidth), packedType, "$_path[$index]");
+      return Reference._(
+          _buffer,
+          elementOffset,
+          BitWidthUtil.fromByteWidth(_byteWidth),
+          packedType,
+          "$_path[$index]",
+          byteWidth,
+          valueType);
     }
     if (key is String && _valueType == ValueType.Map) {
       final index = _keyIndex(key);
@@ -145,13 +168,14 @@ class Reference {
         return _valueForIndexWithKey(index, key);
       }
     }
-    throw ArgumentError('Key: [$key] is not applicable on: $_path of: $_valueType');
+    throw ArgumentError(
+        'Key: [$key] is not applicable on: $_path of: $_valueType');
   }
 
   /// Get an iterable if the underlying flexBuffer value is a vector.
   /// Otherwise throws an exception.
   Iterable<Reference> get vectorIterable {
-    if(isVector == false) {
+    if (isVector == false) {
       throw UnsupportedError('Value is not a vector. It is: $_valueType');
     }
     return _VectorIterator(this);
@@ -160,7 +184,7 @@ class Reference {
   /// Get an iterable for keys if the underlying flexBuffer value is a map.
   /// Otherwise throws an exception.
   Iterable<String> get mapKeyIterable {
-    if(isMap == false) {
+    if (isMap == false) {
       throw UnsupportedError('Value is not a map. It is: $_valueType');
     }
     return _MapKeyIterator(this);
@@ -169,7 +193,7 @@ class Reference {
   /// Get an iterable for values if the underlying flexBuffer value is a map.
   /// Otherwise throws an exception.
   Iterable<Reference> get mapValueIterable {
-    if(isMap == false) {
+    if (isMap == false) {
       throw UnsupportedError('Value is not a map. It is: $_valueType');
     }
     return _MapValueIterator(this);
@@ -181,59 +205,62 @@ class Reference {
   /// If the underlying value is a vector, or map, the length reflects number of elements / element pairs.
   /// If the values is a string or a blob, the length reflects a number of bytes the value occupies (strings are encoded in utf8 format).
   int get length {
-    if (_length != null) {
-      return _length;
-    }
-    // needs to be checked before more generic isAVector
-    if(ValueTypeUtils.isFixedTypedVector(_valueType)) {
-      _length = ValueTypeUtils.fixedTypedVectorElementSize(_valueType);
-    } else if(_valueType == ValueType.Blob || ValueTypeUtils.isAVector(_valueType) || _valueType == ValueType.Map){
-      _length = _readUInt(_indirect - _byteWidth, BitWidthUtil.fromByteWidth(_byteWidth));
-    } else if (_valueType == ValueType.Null) {
-      _length = 0;
-    } else if (_valueType == ValueType.String) {
-      final indirect = _indirect;
-      var size_byte_width = _byteWidth;
-      var size = _readUInt(indirect - size_byte_width, BitWidthUtil.fromByteWidth(size_byte_width));
-      while (_buffer.getInt8(indirect + size) != 0) {
-        size_byte_width <<= 1;
-        size = _readUInt(indirect - size_byte_width, BitWidthUtil.fromByteWidth(size_byte_width));
-      }
-      _length = size;
-    } else if (_valueType == ValueType.Key) {
-      final indirect = _indirect;
-      var size = 1;
-      while (_buffer.getInt8(indirect + size) != 0) {
-        size += 1;
+    if (_length == null) {
+      // needs to be checked before more generic isAVector
+      if (ValueTypeUtils.isFixedTypedVector(_valueType)) {
+        _length = ValueTypeUtils.fixedTypedVectorElementSize(_valueType);
+      } else if (_valueType == ValueType.Blob ||
+          ValueTypeUtils.isAVector(_valueType) ||
+          _valueType == ValueType.Map) {
+        _length = _readUInt(
+            _indirect - _byteWidth, BitWidthUtil.fromByteWidth(_byteWidth));
+      } else if (_valueType == ValueType.Null) {
+        _length = 0;
+      } else if (_valueType == ValueType.String) {
+        final indirect = _indirect;
+        var size_byte_width = _byteWidth;
+        var size = _readUInt(indirect - size_byte_width,
+            BitWidthUtil.fromByteWidth(size_byte_width));
+        while (_buffer.getInt8(indirect + size) != 0) {
+          size_byte_width <<= 1;
+          size = _readUInt(indirect - size_byte_width,
+              BitWidthUtil.fromByteWidth(size_byte_width));
+        }
+        _length = size;
+      } else if (_valueType == ValueType.Key) {
+        final indirect = _indirect;
+        var size = 1;
+        while (_buffer.getInt8(indirect + size) != 0) {
+          size += 1;
+        }
+        _length = size;
+      } else {
+        _length = 1;
       }
-      _length = size;
-    } else {
-      _length = 1;
     }
-    return _length;
+    return _length!;
   }
 
-
   /// Returns a minified JSON representation of the underlying FlexBuffer value.
   ///
   /// This method involves materializing the entire object tree, which may be
   /// expensive. It is more efficient to work with [Reference] and access only the needed data.
   /// Blob values are represented as base64 encoded string.
   String get json {
-    if(_valueType == ValueType.Bool) {
-      return boolValue ? 'true' : 'false';
+    if (_valueType == ValueType.Bool) {
+      return boolValue! ? 'true' : 'false';
     }
     if (_valueType == ValueType.Null) {
       return 'null';
     }
-    if(ValueTypeUtils.isNumber(_valueType)) {
+    if (ValueTypeUtils.isNumber(_valueType)) {
       return jsonEncode(numValue);
     }
     if (_valueType == ValueType.String) {
       return jsonEncode(stringValue);
     }
     if (_valueType == ValueType.Blob) {
-      return jsonEncode(base64Encode(blobValue));
+      return jsonEncode(base64Encode(blobValue!));
     }
     if (ValueTypeUtils.isAVector(_valueType)) {
       final result = StringBuffer();
@@ -261,7 +288,8 @@ class Reference {
       result.write('}');
       return result.toString();
     }
-    throw UnsupportedError('Type: $_valueType is not supported for JSON conversion');
+    throw UnsupportedError(
+        'Type: $_valueType is not supported for JSON conversion');
   }
 
   /// Computes the indirect offset of the value.
@@ -316,16 +344,20 @@ class Reference {
   }
 
   void _validateOffset(int offset, BitWidth width) {
-    if (_offset < 0 || _buffer.lengthInBytes <= offset + width.index || offset & (BitWidthUtil.toByteWidth(width) - 1) != 0) {
+    if (_offset < 0 ||
+        _buffer.lengthInBytes <= offset + width.index ||
+        offset & (BitWidthUtil.toByteWidth(width) - 1) != 0) {
       throw StateError('Bad offset: $offset, width: $width');
     }
   }
 
-  int _keyIndex(String key) {
+  int? _keyIndex(String key) {
     final input = utf8.encode(key);
     final keysVectorOffset = _indirect - _byteWidth * 3;
-    final indirectOffset = keysVectorOffset - _readUInt(keysVectorOffset, BitWidthUtil.fromByteWidth(_byteWidth));
-    final byteWidth = _readUInt(keysVectorOffset + _byteWidth, BitWidthUtil.fromByteWidth(_byteWidth));
+    final indirectOffset = keysVectorOffset -
+        _readUInt(keysVectorOffset, BitWidthUtil.fromByteWidth(_byteWidth));
+    final byteWidth = _readUInt(
+        keysVectorOffset + _byteWidth, BitWidthUtil.fromByteWidth(_byteWidth));
     var low = 0;
     var high = length - 1;
     while (low <= high) {
@@ -341,9 +373,11 @@ class Reference {
     return null;
   }
 
-  int _diffKeys(List<int> input, int index, int indirect_offset, int byteWidth) {
+  int _diffKeys(
+      List<int> input, int index, int indirect_offset, int byteWidth) {
     final keyOffset = indirect_offset + index * byteWidth;
-    final keyIndirectOffset = keyOffset - _readUInt(keyOffset, BitWidthUtil.fromByteWidth(byteWidth));
+    final keyIndirectOffset =
+        keyOffset - _readUInt(keyOffset, BitWidthUtil.fromByteWidth(byteWidth));
     for (var i = 0; i < input.length; i++) {
       final dif = input[i] - _buffer.getUint8(keyIndirectOffset + i);
       if (dif != 0) {
@@ -357,38 +391,42 @@ class Reference {
     final indirect = _indirect;
     final elementOffset = indirect + index * _byteWidth;
     final packedType = _buffer.getUint8(indirect + length * _byteWidth + index);
-    return Reference._(_buffer, elementOffset, BitWidthUtil.fromByteWidth(_byteWidth), packedType, "$_path/$key");
+    return Reference._(_buffer, elementOffset,
+        BitWidthUtil.fromByteWidth(_byteWidth), packedType, "$_path/$key");
   }
 
   Reference _valueForIndex(int index) {
     final indirect = _indirect;
     final elementOffset = indirect + index * _byteWidth;
     final packedType = _buffer.getUint8(indirect + length * _byteWidth + index);
-    return Reference._(_buffer, elementOffset, BitWidthUtil.fromByteWidth(_byteWidth), packedType, "$_path/[$index]");
+    return Reference._(_buffer, elementOffset,
+        BitWidthUtil.fromByteWidth(_byteWidth), packedType, "$_path/[$index]");
   }
 
   String _keyForIndex(int index) {
     final keysVectorOffset = _indirect - _byteWidth * 3;
-    final indirectOffset = keysVectorOffset - _readUInt(keysVectorOffset, BitWidthUtil.fromByteWidth(_byteWidth));
-    final byteWidth = _readUInt(keysVectorOffset + _byteWidth, BitWidthUtil.fromByteWidth(_byteWidth));
+    final indirectOffset = keysVectorOffset -
+        _readUInt(keysVectorOffset, BitWidthUtil.fromByteWidth(_byteWidth));
+    final byteWidth = _readUInt(
+        keysVectorOffset + _byteWidth, BitWidthUtil.fromByteWidth(_byteWidth));
     final keyOffset = indirectOffset + index * byteWidth;
-    final keyIndirectOffset = keyOffset - _readUInt(keyOffset, BitWidthUtil.fromByteWidth(byteWidth));
+    final keyIndirectOffset =
+        keyOffset - _readUInt(keyOffset, BitWidthUtil.fromByteWidth(byteWidth));
     var length = 0;
     while (_buffer.getUint8(keyIndirectOffset + length) != 0) {
       length += 1;
     }
     return utf8.decode(_buffer.buffer.asUint8List(keyIndirectOffset, length));
   }
-
 }
 
-class _VectorIterator with IterableMixin<Reference> implements Iterator<Reference> {
+class _VectorIterator
+    with IterableMixin<Reference>
+    implements Iterator<Reference> {
   final Reference _vector;
-  int index;
+  int index = -1;
 
-  _VectorIterator(this._vector) {
-    index = -1;
-  }
+  _VectorIterator(this._vector);
 
   @override
   Reference get current => _vector[index];
@@ -405,11 +443,9 @@ class _VectorIterator with IterableMixin<Reference> implements Iterator<Referenc
 
 class _MapKeyIterator with IterableMixin<String> implements Iterator<String> {
   final Reference _map;
-  int index;
+  int index = -1;
 
-  _MapKeyIterator(this._map) {
-    index = -1;
-  }
+  _MapKeyIterator(this._map);
 
   @override
   String get current => _map._keyForIndex(index);
@@ -424,13 +460,13 @@ class _MapKeyIterator with IterableMixin<String> implements Iterator<String> {
   Iterator<String> get iterator => this;
 }
 
-class _MapValueIterator with IterableMixin<Reference> implements Iterator<Reference> {
+class _MapValueIterator
+    with IterableMixin<Reference>
+    implements Iterator<Reference> {
   final Reference _map;
-  int index;
+  int index = -1;
 
-  _MapValueIterator(this._map) {
-    index = -1;
-  }
+  _MapValueIterator(this._map);
 
   @override
   Reference get current => _map._valueForIndex(index);
diff --git a/dart/lib/src/types.dart b/dart/lib/src/types.dart
index 8aed2725..bc9bb3ac 100644
--- a/dart/lib/src/types.dart
+++ b/dart/lib/src/types.dart
@@ -1,17 +1,13 @@
 import 'dart:typed_data';
 
 /// Represents the number of bits a value occupies.
-enum BitWidth {
-  width8,
-  width16,
-  width32,
-  width64
-}
+enum BitWidth { width8, width16, width32, width64 }
 
 class BitWidthUtil {
   static int toByteWidth(BitWidth self) {
     return 1 << self.index;
   }
+
   static BitWidth width(num value) {
     if (value.toInt() == value) {
       var v = value.toInt().abs();
@@ -20,8 +16,11 @@ class BitWidthUtil {
       if (v >> 31 == 0) return BitWidth.width32;
       return BitWidth.width64;
     }
-    return value == _toF32(value) ? BitWidth.width32 : BitWidth.width64;
+    return value == _toF32(value as double)
+        ? BitWidth.width32
+        : BitWidth.width64;
   }
+
   static BitWidth uwidth(num value) {
     if (value.toInt() == value) {
       var v = value.toInt().abs();
@@ -30,8 +29,11 @@ class BitWidthUtil {
       if (v >> 32 == 0) return BitWidth.width32;
       return BitWidth.width64;
     }
-    return value == _toF32(value) ? BitWidth.width32 : BitWidth.width64;
+    return value == _toF32(value as double)
+        ? BitWidth.width32
+        : BitWidth.width64;
   }
+
   static BitWidth fromByteWidth(int value) {
     if (value == 1) {
       return BitWidth.width8;
@@ -47,9 +49,11 @@ class BitWidthUtil {
     }
     throw Exception('Unexpected value ${value}');
   }
+
   static int paddingSize(int bufSize, int scalarSize) {
     return (~bufSize + 1) & (scalarSize - 1);
   }
+
   static double _toF32(double value) {
     var bdata = ByteData(4);
     bdata.setFloat32(0, value);
@@ -66,15 +70,36 @@ class BitWidthUtil {
 
 /// Represents all internal FlexBuffer types.
 enum ValueType {
-  Null, Int, UInt, Float,
-  Key, String, IndirectInt, IndirectUInt, IndirectFloat,
-  Map, Vector, VectorInt, VectorUInt, VectorFloat, VectorKey,
-  @Deprecated('VectorString is deprecated due to a flaw in the binary format (https://github.com/google/flatbuffers/issues/5627)')
+  Null,
+  Int,
+  UInt,
+  Float,
+  Key,
+  String,
+  IndirectInt,
+  IndirectUInt,
+  IndirectFloat,
+  Map,
+  Vector,
+  VectorInt,
+  VectorUInt,
+  VectorFloat,
+  VectorKey,
+  @Deprecated(
+      'VectorString is deprecated due to a flaw in the binary format (https://github.com/google/flatbuffers/issues/5627)')
   VectorString,
-  VectorInt2, VectorUInt2, VectorFloat2,
-  VectorInt3, VectorUInt3, VectorFloat3,
-  VectorInt4, VectorUInt4, VectorFloat4,
-  Blob, Bool, VectorBool
+  VectorInt2,
+  VectorUInt2,
+  VectorFloat2,
+  VectorInt3,
+  VectorUInt3,
+  VectorFloat3,
+  VectorInt4,
+  VectorUInt4,
+  VectorFloat4,
+  Blob,
+  Bool,
+  VectorBool
 }
 
 class ValueTypeUtils {
@@ -89,71 +114,70 @@ class ValueTypeUtils {
   }
 
   static bool isInline(ValueType self) {
-    return self == ValueType.Bool
-        || toInt(self) <= toInt(ValueType.Float);
+    return self == ValueType.Bool || toInt(self) <= toInt(ValueType.Float);
   }
 
   static bool isNumber(ValueType self) {
-    return toInt(self) >= toInt(ValueType.Int)
-        && toInt(self) <= toInt(ValueType.Float);
+    return toInt(self) >= toInt(ValueType.Int) &&
+        toInt(self) <= toInt(ValueType.Float);
   }
 
   static bool isIndirectNumber(ValueType self) {
-    return toInt(self) >= toInt(ValueType.IndirectInt)
-        && toInt(self) <= toInt(ValueType.IndirectFloat);
+    return toInt(self) >= toInt(ValueType.IndirectInt) &&
+        toInt(self) <= toInt(ValueType.IndirectFloat);
   }
 
   static bool isTypedVectorElement(ValueType self) {
     return self == ValueType.Bool ||
-        (
-            toInt(self) >= toInt(ValueType.Int)
-            && toInt(self) <= toInt(ValueType.String)
-        );
+        (toInt(self) >= toInt(ValueType.Int) &&
+            toInt(self) <= toInt(ValueType.String));
   }
 
   static bool isTypedVector(ValueType self) {
     return self == ValueType.VectorBool ||
-        (
-          toInt(self) >= toInt(ValueType.VectorInt)
-              && toInt(self) <= toInt(ValueType.VectorString)
-        );
+        (toInt(self) >= toInt(ValueType.VectorInt) &&
+            toInt(self) <= toInt(ValueType.VectorString));
   }
 
   static bool isFixedTypedVector(ValueType self) {
-    return (
-            toInt(self) >= toInt(ValueType.VectorInt2)
-                && toInt(self) <= toInt(ValueType.VectorFloat4)
-        );
+    return (toInt(self) >= toInt(ValueType.VectorInt2) &&
+        toInt(self) <= toInt(ValueType.VectorFloat4));
   }
 
   static bool isAVector(ValueType self) {
-    return (
-        isTypedVector(self) || isFixedTypedVector(self) || self == ValueType.Vector
-    );
+    return (isTypedVector(self) ||
+        isFixedTypedVector(self) ||
+        self == ValueType.Vector);
   }
 
   static ValueType toTypedVector(ValueType self, int length) {
     if (length == 0) {
-      return ValueTypeUtils.fromInt(toInt(self) - toInt(ValueType.Int) + toInt(ValueType.VectorInt));
+      return ValueTypeUtils.fromInt(
+          toInt(self) - toInt(ValueType.Int) + toInt(ValueType.VectorInt));
     }
     if (length == 2) {
-      return ValueTypeUtils.fromInt(toInt(self) - toInt(ValueType.Int) + toInt(ValueType.VectorInt2));
+      return ValueTypeUtils.fromInt(
+          toInt(self) - toInt(ValueType.Int) + toInt(ValueType.VectorInt2));
     }
     if (length == 3) {
-      return ValueTypeUtils.fromInt(toInt(self) - toInt(ValueType.Int) + toInt(ValueType.VectorInt3));
+      return ValueTypeUtils.fromInt(
+          toInt(self) - toInt(ValueType.Int) + toInt(ValueType.VectorInt3));
     }
     if (length == 4) {
-      return ValueTypeUtils.fromInt(toInt(self) - toInt(ValueType.Int) + toInt(ValueType.VectorInt4));
+      return ValueTypeUtils.fromInt(
+          toInt(self) - toInt(ValueType.Int) + toInt(ValueType.VectorInt4));
     }
     throw Exception('unexpected length ' + length.toString());
   }
 
   static ValueType typedVectorElementType(ValueType self) {
-    return ValueTypeUtils.fromInt(toInt(self) - toInt(ValueType.VectorInt) + toInt(ValueType.Int));
+    return ValueTypeUtils.fromInt(
+        toInt(self) - toInt(ValueType.VectorInt) + toInt(ValueType.Int));
   }
 
   static ValueType fixedTypedVectorElementType(ValueType self) {
-    return ValueTypeUtils.fromInt((toInt(self) - toInt(ValueType.VectorInt2)) % 3 + toInt(ValueType.Int));
+    return ValueTypeUtils.fromInt(
+        (toInt(self) - toInt(ValueType.VectorInt2)) % 3 + toInt(ValueType.Int));
   }
 
   static int fixedTypedVectorElementSize(ValueType self) {
diff --git a/dart/pubspec.yaml b/dart/pubspec.yaml
index c13d3ce9..38738f55 100644
--- a/dart/pubspec.yaml
+++ b/dart/pubspec.yaml
@@ -13,8 +13,8 @@ authors:
 homepage: https://github.com/google/flatbuffers
 documentation: https://google.github.io/flatbuffers/index.html
 dev_dependencies:
-  test: ^1.3.0
-  test_reflective_loader: ^0.1.4
-  path: ^1.5.1
+  test: ^1.17.7
+  test_reflective_loader: ^0.2.0
+  path: ^1.8.0
 environment:
-  sdk: '>=2.0.0-dev.28.0 <3.0.0'
\ No newline at end of file
+  sdk: '>=2.12.0 <3.0.0'
diff --git a/dart/test/flat_buffers_test.dart b/dart/test/flat_buffers_test.dart
index 0e8c7572..c2121a0f 100644
--- a/dart/test/flat_buffers_test.dart
+++ b/dart/test/flat_buffers_test.dart
@@ -39,26 +39,26 @@ class CheckOtherLangaugesData {
     expect(mon.hp, 80);
     expect(mon.mana, 150);
     expect(mon.name, 'MyMonster');
-    expect(mon.pos.x, 1.0);
-    expect(mon.pos.y, 2.0);
-    expect(mon.pos.z, 3.0);
-    expect(mon.pos.test1, 3.0);
-    expect(mon.pos.test2.value, 2.0);
-    expect(mon.pos.test3.a, 5);
-    expect(mon.pos.test3.b, 6);
-    expect(mon.testType.value, example.AnyTypeId.Monster.value);
+    expect(mon.pos!.x, 1.0);
+    expect(mon.pos!.y, 2.0);
+    expect(mon.pos!.z, 3.0);
+    expect(mon.pos!.test1, 3.0);
+    expect(mon.pos!.test2.value, 2.0);
+    expect(mon.pos!.test3.a, 5);
+    expect(mon.pos!.test3.b, 6);
+    expect(mon.testType!.value, example.AnyTypeId.Monster.value);
     expect(mon.test is example.Monster, true);
     final monster2 = mon.test as example.Monster;
     expect(monster2.name, "Fred");
 
-    expect(mon.inventory.length, 5);
-    expect(mon.inventory.reduce((cur, next) => cur + next), 10);
-    expect(mon.test4.length, 2);
-    expect(
-        mon.test4[0].a + mon.test4[0].b + mon.test4[1].a + mon.test4[1].b, 100);
-    expect(mon.testarrayofstring.length, 2);
-    expect(mon.testarrayofstring[0], "test1");
-    expect(mon.testarrayofstring[1], "test2");
+    expect(mon.inventory!.length, 5);
+    expect(mon.inventory!.reduce((cur, next) => cur + next), 10);
+    final test4 = mon.test4!;
+    expect(test4.length, 2);
+    expect(test4[0].a + test4[0].b + test4[1].a + test4[1].b, 100);
+    expect(mon.testarrayofstring!.length, 2);
+    expect(mon.testarrayofstring![0], "test1");
+    expect(mon.testarrayofstring![1], "test2");
 
     // this will fail if accessing any field fails.
     expect(
@@ -68,7 +68,7 @@ class CheckOtherLangaugesData {
       'mana: 150, hp: 80, name: MyMonster, inventory: [0, 1, 2, 3, 4], '
       'color: Color{value: 8}, testType: AnyTypeId{value: 1}, '
       'test: Monster{pos: null, mana: 150, hp: 100, name: Fred, '
-      'inventory: null, color: Color{value: 8}, testType: AnyTypeId{value: 0}, '
+      'inventory: null, color: Color{value: 8}, testType: null, '
       'test: null, test4: null, testarrayofstring: null, '
       'testarrayoftables: null, enemy: null, testnestedflatbuffer: null, '
       'testempty: null, testbool: false, testhashs32Fnv1: 0, '
@@ -82,14 +82,13 @@ class CheckOtherLangaugesData {
       'vectorOfWeakReferences: null, vectorOfStrongReferrables: null, '
       'coOwningReference: 0, vectorOfCoOwningReferences: null, '
       'nonOwningReference: 0, vectorOfNonOwningReferences: null, '
-      'anyUniqueType: AnyUniqueAliasesTypeId{value: 0}, anyUnique: null, '
-      'anyAmbiguousType: AnyAmbiguousAliasesTypeId{value: 0}, '
+      'anyUniqueType: null, anyUnique: null, anyAmbiguousType: null, '
       'anyAmbiguous: null, vectorOfEnums: null, signedEnum: Race{value: -1}, '
       'testrequirednestedflatbuffer: null, scalarKeySortedTables: null}, '
       'test4: [Test{a: 10, b: 20}, Test{a: 30, b: 40}], '
       'testarrayofstring: [test1, test2], testarrayoftables: null, '
       'enemy: Monster{pos: null, mana: 150, hp: 100, name: Fred, '
-      'inventory: null, color: Color{value: 8}, testType: AnyTypeId{value: 0}, '
+      'inventory: null, color: Color{value: 8}, testType: null, '
       'test: null, test4: null, testarrayofstring: null, '
       'testarrayoftables: null, enemy: null, testnestedflatbuffer: null, '
       'testempty: null, testbool: false, testhashs32Fnv1: 0, '
@@ -103,8 +102,7 @@ class CheckOtherLangaugesData {
       'vectorOfWeakReferences: null, vectorOfStrongReferrables: null, '
       'coOwningReference: 0, vectorOfCoOwningReferences: null, '
       'nonOwningReference: 0, vectorOfNonOwningReferences: null, '
-      'anyUniqueType: AnyUniqueAliasesTypeId{value: 0}, anyUnique: null, '
-      'anyAmbiguousType: AnyAmbiguousAliasesTypeId{value: 0}, '
+      'anyUniqueType: null, anyUnique: null, anyAmbiguousType: null, '
       'anyAmbiguous: null, vectorOfEnums: null, signedEnum: Race{value: -1}, '
       'testrequirednestedflatbuffer: null, scalarKeySortedTables: null}, '
       'testnestedflatbuffer: null, testempty: null, testbool: true, '
@@ -126,8 +124,8 @@ class CheckOtherLangaugesData {
       'vectorOfStrongReferrables: null, coOwningReference: 0, '
       'vectorOfCoOwningReferences: null, nonOwningReference: 0, '
       'vectorOfNonOwningReferences: null, '
-      'anyUniqueType: AnyUniqueAliasesTypeId{value: 0}, anyUnique: null, '
-      'anyAmbiguousType: AnyAmbiguousAliasesTypeId{value: 0}, '
+      'anyUniqueType: null, anyUnique: null, '
+      'anyAmbiguousType: null, '
       'anyAmbiguous: null, vectorOfEnums: null, signedEnum: Race{value: -1}, '
       'testrequirednestedflatbuffer: null, scalarKeySortedTables: [Stat{id: '
       'miss, val: 0, count: 0}, Stat{id: hit, val: 10, count: 1}]}',
@@ -137,7 +135,7 @@ class CheckOtherLangaugesData {
 
 @reflectiveTest
 class BuilderTest {
-  void test_monsterBuilder([Builder builder]) {
+  void test_monsterBuilder([Builder? builder]) {
     final fbBuilder = builder ?? new Builder();
     final str = fbBuilder.writeString('MyMonster');
 
@@ -183,10 +181,10 @@ class BuilderTest {
     fbBuilder.finish(mon);
   }
 
-  void test_error_addInt32_withoutStartTable([Builder builder]) {
+  void test_error_addInt32_withoutStartTable([Builder? builder]) {
     builder ??= new Builder();
     expect(() {
-      builder.addInt32(0, 0);
+      builder!.addInt32(0, 0);
     }, throwsStateError);
   }
 
@@ -288,7 +286,7 @@ class BuilderTest {
         20);
   }
 
-  void test_table_format([Builder builder]) {
+  void test_table_format([Builder? builder]) {
     Uint8List byteList;
     {
       builder ??= new Builder(initialSize: 0);
@@ -326,8 +324,8 @@ class BuilderTest {
     List<int> byteList;
     {
       Builder builder = new Builder(initialSize: 0);
-      int latinStringOffset = builder.writeString(latinString);
-      int unicodeStringOffset = builder.writeString(unicodeString);
+      int? latinStringOffset = builder.writeString(latinString);
+      int? unicodeStringOffset = builder.writeString(unicodeString);
       builder.startTable();
       builder.addOffset(0, latinStringOffset);
       builder.addOffset(1, unicodeStringOffset);
@@ -337,17 +335,21 @@ class BuilderTest {
     // read and verify
     BufferContext buf = new BufferContext.fromBytes(byteList);
     int objectOffset = buf.derefObject(0);
-    expect(const StringReader().vTableGet(buf, objectOffset, indexToField(0)),
+    expect(
+        const StringReader()
+            .vTableGetNullable(buf, objectOffset, indexToField(0)),
         latinString);
-    expect(const StringReader().vTableGet(buf, objectOffset, indexToField(1)),
+    expect(
+        const StringReader()
+            .vTableGetNullable(buf, objectOffset, indexToField(1)),
         unicodeString);
   }
 
-  void test_table_types([Builder builder]) {
+  void test_table_types([Builder? builder]) {
     List<int> byteList;
     {
       builder ??= new Builder(initialSize: 0);
-      int stringOffset = builder.writeString('12345');
+      int? stringOffset = builder.writeString('12345');
       builder.startTable();
       builder.addBool(0, true);
       builder.addInt8(1, 10);
@@ -363,18 +365,32 @@ class BuilderTest {
     BufferContext buf = new BufferContext.fromBytes(byteList);
     int objectOffset = buf.derefObject(0);
     expect(
-        const BoolReader().vTableGet(buf, objectOffset, indexToField(0)), true);
+        const BoolReader()
+            .vTableGetNullable(buf, objectOffset, indexToField(0)),
+        true);
     expect(
-        const Int8Reader().vTableGet(buf, objectOffset, indexToField(1)), 10);
+        const Int8Reader()
+            .vTableGetNullable(buf, objectOffset, indexToField(1)),
+        10);
     expect(
-        const Int32Reader().vTableGet(buf, objectOffset, indexToField(2)), 20);
-    expect(const StringReader().vTableGet(buf, objectOffset, indexToField(3)),
+        const Int32Reader()
+            .vTableGetNullable(buf, objectOffset, indexToField(2)),
+        20);
+    expect(
+        const StringReader()
+            .vTableGetNullable(buf, objectOffset, indexToField(3)),
         '12345');
     expect(
-        const Int32Reader().vTableGet(buf, objectOffset, indexToField(4)), 40);
-    expect(const Uint32Reader().vTableGet(buf, objectOffset, indexToField(5)),
+        const Int32Reader()
+            .vTableGetNullable(buf, objectOffset, indexToField(4)),
+        40);
+    expect(
+        const Uint32Reader()
+            .vTableGetNullable(buf, objectOffset, indexToField(5)),
         0x9ABCDEF0);
-    expect(const Uint8Reader().vTableGet(buf, objectOffset, indexToField(6)),
+    expect(
+        const Uint8Reader()
+            .vTableGetNullable(buf, objectOffset, indexToField(6)),
         0x9A);
   }
 
@@ -488,7 +504,7 @@ class BuilderTest {
     }
   }
 
-  void test_writeList_ofObjects([Builder builder]) {
+  void test_writeList_ofObjects([Builder? builder]) {
     List<int> byteList;
     {
       builder ??= new Builder(initialSize: 0);
@@ -527,9 +543,9 @@ class BuilderTest {
     List<int> byteList;
     {
       Builder builder = new Builder(initialSize: 0);
-      int str1 = builder.writeString('12345');
-      int str2 = builder.writeString('ABC');
-      int offset = builder.writeList([str1, str2]);
+      int? str1 = builder.writeString('12345');
+      int? str2 = builder.writeString('ABC');
+      int offset = builder.writeList([str1!, str2!]);
       byteList = builder.finish(offset);
     }
     // read and verify
@@ -541,12 +557,12 @@ class BuilderTest {
     expect(items, contains('ABC'));
   }
 
-  void test_writeList_ofStrings_inObject([Builder builder]) {
+  void test_writeList_ofStrings_inObject([Builder? builder]) {
     List<int> byteList;
     {
       builder ??= new Builder(initialSize: 0);
       int listOffset = builder.writeList(
-          [builder.writeString('12345'), builder.writeString('ABC')]);
+          [builder.writeString('12345')!, builder.writeString('ABC')!]);
       builder.startTable();
       builder.addOffset(0, listOffset);
       int offset = builder.endTable();
@@ -555,7 +571,7 @@ class BuilderTest {
     // read and verify
     BufferContext buf = new BufferContext.fromBytes(byteList);
     StringListWrapperImpl reader = new StringListWrapperReader().read(buf, 0);
-    List<String> items = reader.items;
+    List<String>? items = reader.items;
     expect(items, hasLength(2));
     expect(items, contains('12345'));
     expect(items, contains('ABC'));
@@ -605,7 +621,7 @@ class BuilderTest {
 
   void test_reset() {
     // We'll run a selection of tests , reusing the builder between them.
-    final testCases = <void Function(Builder)>[
+    final testCases = <void Function(Builder?)>[
       test_monsterBuilder,
       test_error_addInt32_withoutStartTable,
       test_table_format,
@@ -624,14 +640,14 @@ class BuilderTest {
       // print the order so failures are reproducible
       printOnFailure('Running reset() test cases in order: $indexes');
 
-      Builder builder;
+      Builder? builder;
       indexes.forEach((index) {
         if (builder == null) {
           // Initial size small enough so at least one test case increases it.
           // On the other hand, it's large enough so that some test cases don't.
           builder = Builder(initialSize: 32);
         } else {
-          builder.reset();
+          builder!.reset();
         }
         testCases[index](builder);
       });
@@ -739,8 +755,8 @@ class StringListWrapperImpl {
 
   StringListWrapperImpl(this.bp, this.offset);
 
-  List<String> get items => const ListReader<String>(const StringReader())
-      .vTableGet(bp, offset, indexToField(0));
+  List<String>? get items => const ListReader<String>(const StringReader())
+      .vTableGetNullable(bp, offset, indexToField(0));
 }
 
 class StringListWrapperReader extends TableReader<StringListWrapperImpl> {
diff --git a/dart/test/flex_builder_test.dart b/dart/test/flex_builder_test.dart
index 5a1c1a8f..66e66384 100644
--- a/dart/test/flex_builder_test.dart
+++ b/dart/test/flex_builder_test.dart
@@ -58,18 +58,18 @@ void main() {
     {
       var flx = Builder();
       flx.addString('hello 😱');
-      expect(flx.finish(), [10, 104, 101, 108, 108, 111, 32, 240, 159, 152, 177, 0, 11, 20, 1]);
+      expect(flx.finish(),
+          [10, 104, 101, 108, 108, 111, 32, 240, 159, 152, 177, 0, 11, 20, 1]);
     }
   });
 
-  test('build vector', (){
+  test('build vector', () {
     {
       var flx = Builder()
         ..startVector()
         ..addInt(1)
         ..addInt(2)
-        ..end()
-      ;
+        ..end();
       expect(flx.finish(), [1, 2, 2, 64, 1]);
     }
     {
@@ -77,8 +77,7 @@ void main() {
         ..startVector()
         ..addInt(-1)
         ..addInt(256)
-        ..end()
-      ;
+        ..end();
       expect(flx.finish(), [255, 255, 0, 1, 4, 65, 1]);
     }
     {
@@ -86,8 +85,7 @@ void main() {
         ..startVector()
         ..addInt(-45)
         ..addInt(256000)
-        ..end()
-      ;
+        ..end();
       expect(flx.finish(), [211, 255, 255, 255, 0, 232, 3, 0, 8, 66, 1]);
     }
     {
@@ -95,9 +93,28 @@ void main() {
         ..startVector()
         ..addDouble(1.1)
         ..addDouble(-256)
-        ..end()
-      ;
-      expect(flx.finish(), [154, 153, 153, 153, 153, 153, 241, 63, 0, 0, 0, 0, 0, 0, 112, 192, 16, 75, 1]);
+        ..end();
+      expect(flx.finish(), [
+        154,
+        153,
+        153,
+        153,
+        153,
+        153,
+        241,
+        63,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        112,
+        192,
+        16,
+        75,
+        1
+      ]);
     }
     {
       var flx = Builder()
@@ -105,8 +122,7 @@ void main() {
         ..addInt(1)
         ..addInt(2)
         ..addInt(4)
-        ..end()
-      ;
+        ..end();
       expect(flx.finish(), [1, 2, 4, 3, 76, 1]);
     }
     {
@@ -115,19 +131,17 @@ void main() {
         ..addInt(-1)
         ..addInt(256)
         ..addInt(4)
-        ..end()
-      ;
+        ..end();
       expect(flx.finish(), [255, 255, 0, 1, 4, 0, 6, 77, 1]);
     }
     {
       var flx = Builder()
         ..startVector()
-          ..startVector()
-          ..addInt(61)
-          ..end()
-        ..addInt(64)
+        ..startVector()
+        ..addInt(61)
         ..end()
-      ;
+        ..addInt(64)
+        ..end();
       expect(flx.finish(), [1, 61, 2, 2, 64, 44, 4, 4, 40, 1]);
     }
     {
@@ -136,9 +150,31 @@ void main() {
         ..addString('foo')
         ..addString('bar')
         ..addString('baz')
-        ..end()
-      ;
-      expect(flx.finish(), [3, 102, 111, 111, 0, 3, 98, 97, 114, 0, 3, 98, 97, 122, 0, 3, 15, 11, 7, 3, 60, 1]);
+        ..end();
+      expect(flx.finish(), [
+        3,
+        102,
+        111,
+        111,
+        0,
+        3,
+        98,
+        97,
+        114,
+        0,
+        3,
+        98,
+        97,
+        122,
+        0,
+        3,
+        15,
+        11,
+        7,
+        3,
+        60,
+        1
+      ]);
     }
     {
       var flx = Builder()
@@ -149,9 +185,34 @@ void main() {
         ..addString('foo')
         ..addString('bar')
         ..addString('baz')
-        ..end()
-      ;
-      expect(flx.finish(), [3, 102, 111, 111, 0, 3, 98, 97, 114, 0, 3, 98, 97, 122, 0, 6, 15, 11, 7, 18, 14, 10, 6, 60, 1]);
+        ..end();
+      expect(flx.finish(), [
+        3,
+        102,
+        111,
+        111,
+        0,
+        3,
+        98,
+        97,
+        114,
+        0,
+        3,
+        98,
+        97,
+        122,
+        0,
+        6,
+        15,
+        11,
+        7,
+        18,
+        14,
+        10,
+        6,
+        60,
+        1
+      ]);
     }
     {
       var flx = Builder()
@@ -159,8 +220,7 @@ void main() {
         ..addBool(true)
         ..addBool(false)
         ..addBool(true)
-        ..end()
-      ;
+        ..end();
       expect(flx.finish(), [3, 1, 0, 1, 3, 144, 1]);
     }
     {
@@ -171,29 +231,83 @@ void main() {
         ..addInt(-5)
         ..addDouble(1.3)
         ..addBool(true)
-        ..end()
-      ;
+        ..end();
       expect(flx.finish(), [
-        3, 102, 111, 111, 0, 0, 0, 0,
-        5, 0, 0, 0, 0, 0, 0, 0,
-        15, 0, 0, 0, 0, 0, 0, 0,
-        1, 0, 0, 0, 0, 0, 0, 0,
-        251, 255, 255, 255, 255, 255, 255, 255,
-        205, 204, 204, 204, 204, 204, 244, 63,
-        1, 0, 0, 0, 0, 0, 0, 0,
-        20, 4, 4, 15, 104, 45, 43, 1]);
+        3,
+        102,
+        111,
+        111,
+        0,
+        0,
+        0,
+        0,
+        5,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        15,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        1,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        251,
+        255,
+        255,
+        255,
+        255,
+        255,
+        255,
+        255,
+        205,
+        204,
+        204,
+        204,
+        204,
+        204,
+        244,
+        63,
+        1,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        20,
+        4,
+        4,
+        15,
+        104,
+        45,
+        43,
+        1
+      ]);
     }
   });
 
-  test('build map', ()
-  {
+  test('build map', () {
     {
       var flx = Builder()
         ..startMap()
         ..addKey('a')
         ..addInt(12)
-        ..end()
-      ;
+        ..end();
       expect(flx.finish(), [97, 0, 1, 3, 1, 1, 1, 12, 4, 2, 36, 1]);
     }
     {
@@ -203,105 +317,270 @@ void main() {
         ..addInt(12)
         ..addKey('')
         ..addInt(45)
-        ..end()
-      ;
-      expect(flx.finish(), [97, 0, 0, 2, 2, 5, 2, 1, 2, 45, 12, 4, 4, 4, 36, 1]);
+        ..end();
+      expect(
+          flx.finish(), [97, 0, 0, 2, 2, 5, 2, 1, 2, 45, 12, 4, 4, 4, 36, 1]);
     }
     {
       var flx = Builder()
         ..startVector()
-          ..startMap()
-            ..addKey('something')
-            ..addInt(12)
-          ..end()
-          ..startMap()
-            ..addKey('something')
-            ..addInt(45)
-          ..end()
+        ..startMap()
+        ..addKey('something')
+        ..addInt(12)
         ..end()
-      ;
-      expect(flx.finish(), [115, 111, 109, 101, 116, 104, 105, 110, 103, 0,
-        1, 11, 1, 1, 1, 12, 4, 6, 1, 1, 45, 4, 2, 8, 4, 36, 36, 4, 40, 1]);
+        ..startMap()
+        ..addKey('something')
+        ..addInt(45)
+        ..end()
+        ..end();
+      expect(flx.finish(), [
+        115,
+        111,
+        109,
+        101,
+        116,
+        104,
+        105,
+        110,
+        103,
+        0,
+        1,
+        11,
+        1,
+        1,
+        1,
+        12,
+        4,
+        6,
+        1,
+        1,
+        45,
+        4,
+        2,
+        8,
+        4,
+        36,
+        36,
+        4,
+        40,
+        1
+      ]);
     }
   });
 
-  test('build blob', ()
-  {
+  test('build blob', () {
     {
-      var flx = Builder()
-        ..addBlob(Uint8List.fromList([1, 2, 3]).buffer)
-      ;
+      var flx = Builder()..addBlob(Uint8List.fromList([1, 2, 3]).buffer);
       expect(flx.finish(), [3, 1, 2, 3, 3, 100, 1]);
     }
   });
 
-  test('build from object', (){
-    expect(Builder.buildFromObject(Uint8List.fromList([1, 2, 3]).buffer).asUint8List(), [3, 1, 2, 3, 3, 100, 1]);
+  test('build from object', () {
+    expect(
+        Builder.buildFromObject(Uint8List.fromList([1, 2, 3]).buffer)
+            .asUint8List(),
+        [3, 1, 2, 3, 3, 100, 1]);
     expect(Builder.buildFromObject(null).asUint8List(), [0, 0, 1]);
     expect(Builder.buildFromObject(true).asUint8List(), [1, 104, 1]);
     expect(Builder.buildFromObject(false).asUint8List(), [0, 104, 1]);
     expect(Builder.buildFromObject(25).asUint8List(), [25, 4, 1]);
     expect(Builder.buildFromObject(-250).asUint8List(), [6, 255, 5, 2]);
-    expect(Builder.buildFromObject(-2.50).asUint8List(), [0, 0, 32, 192, 14, 4]);
-    expect(Builder.buildFromObject('Maxim').asUint8List(), [5, 77, 97, 120, 105, 109, 0, 6, 20, 1]);
-    expect(Builder.buildFromObject([1, 3.3, 'max', true, null, false]).asUint8List(), [
-      3, 109, 97, 120, 0, 0, 0, 0,
-      6, 0, 0, 0, 0, 0, 0, 0,
-      1, 0, 0, 0, 0, 0, 0, 0,
-      102, 102, 102, 102, 102, 102, 10, 64,
-      31, 0, 0, 0, 0, 0, 0, 0,
-      1, 0, 0, 0, 0, 0, 0, 0,
-      0, 0, 0, 0, 0, 0, 0, 0,
-      0, 0, 0, 0, 0, 0, 0, 0,
-      4, 15, 20, 104, 0, 104, 54, 43, 1
-    ]);
-    expect(Builder.buildFromObject([{'something':12}, {'something': 45}]).asUint8List(), [
-      115, 111, 109, 101, 116, 104, 105, 110, 103, 0,
-      1, 11, 1, 1, 1, 12, 4, 6, 1, 1, 45, 4, 2, 8, 4, 36, 36, 4, 40, 1
-    ]);
+    expect(
+        Builder.buildFromObject(-2.50).asUint8List(), [0, 0, 32, 192, 14, 4]);
+    expect(Builder.buildFromObject('Maxim').asUint8List(),
+        [5, 77, 97, 120, 105, 109, 0, 6, 20, 1]);
+    expect(
+        Builder.buildFromObject([1, 3.3, 'max', true, null, false])
+            .asUint8List(),
+        [
+          3,
+          109,
+          97,
+          120,
+          0,
+          0,
+          0,
+          0,
+          6,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          1,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          102,
+          102,
+          102,
+          102,
+          102,
+          102,
+          10,
+          64,
+          31,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          1,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          4,
+          15,
+          20,
+          104,
+          0,
+          104,
+          54,
+          43,
+          1
+        ]);
+    expect(
+        Builder.buildFromObject([
+          {'something': 12},
+          {'something': 45}
+        ]).asUint8List(),
+        [
+          115,
+          111,
+          109,
+          101,
+          116,
+          104,
+          105,
+          110,
+          103,
+          0,
+          1,
+          11,
+          1,
+          1,
+          1,
+          12,
+          4,
+          6,
+          1,
+          1,
+          45,
+          4,
+          2,
+          8,
+          4,
+          36,
+          36,
+          4,
+          40,
+          1
+        ]);
   });
 
-  test('add double indirectly', (){
-    var flx = Builder()
-      ..addDoubleIndirectly(0.1)
-    ;
+  test('add double indirectly', () {
+    var flx = Builder()..addDoubleIndirectly(0.1);
     expect(flx.finish(), [154, 153, 153, 153, 153, 153, 185, 63, 8, 35, 1]);
   });
 
-  test('add double indirectly to vector with cache', (){
+  test('add double indirectly to vector with cache', () {
     var flx = Builder()
       ..startVector()
       ..addDoubleIndirectly(0.1, cache: true)
       ..addDoubleIndirectly(0.1, cache: true)
       ..addDoubleIndirectly(0.1, cache: true)
       ..addDoubleIndirectly(0.1, cache: true)
-      ..end()
-    ;
-    expect(flx.finish(), [154, 153, 153, 153, 153, 153, 185, 63,
-      4, 9, 10, 11, 12, 35, 35, 35, 35, 8, 40, 1]);
+      ..end();
+    expect(flx.finish(), [
+      154,
+      153,
+      153,
+      153,
+      153,
+      153,
+      185,
+      63,
+      4,
+      9,
+      10,
+      11,
+      12,
+      35,
+      35,
+      35,
+      35,
+      8,
+      40,
+      1
+    ]);
   });
 
-  test('add int indirectly', (){
-    var flx = Builder()
-      ..addIntIndirectly(2345234523452345)
-    ;
+  test('add int indirectly', () {
+    var flx = Builder()..addIntIndirectly(2345234523452345);
     expect(flx.finish(), [185, 115, 175, 118, 250, 84, 8, 0, 8, 27, 1]);
   });
 
-  test('add int indirectly to vector with cache', (){
+  test('add int indirectly to vector with cache', () {
     var flx = Builder()
       ..startVector()
       ..addIntIndirectly(2345234523452345, cache: true)
       ..addIntIndirectly(2345234523452345, cache: true)
       ..addIntIndirectly(2345234523452345, cache: true)
       ..addIntIndirectly(2345234523452345, cache: true)
-      ..end()
-    ;
-    expect(flx.finish(), [185, 115, 175, 118, 250, 84, 8, 0,
-      4, 9, 10, 11, 12, 27, 27, 27, 27, 8, 40, 1]);
+      ..end();
+    expect(flx.finish(), [
+      185,
+      115,
+      175,
+      118,
+      250,
+      84,
+      8,
+      0,
+      4,
+      9,
+      10,
+      11,
+      12,
+      27,
+      27,
+      27,
+      27,
+      8,
+      40,
+      1
+    ]);
   });
 
-  test('snapshot', (){
+  test('snapshot', () {
     var flx = Builder();
     flx.startVector();
     flx.addInt(12);
@@ -312,4 +591,3 @@ void main() {
     expect(flx.snapshot().asUint8List(), [12, 24, 45, 3, 76, 1]);
   });
 }
-
diff --git a/dart/test/flex_reader_test.dart b/dart/test/flex_reader_test.dart
index ec30367b..875b1c16 100644
--- a/dart/test/flex_reader_test.dart
+++ b/dart/test/flex_reader_test.dart
@@ -21,55 +21,68 @@ void main() {
     expect(Reference.fromBuffer(b([255, 251, 5, 2])).intValue, -1025);
     expect(Reference.fromBuffer(b([1, 4, 9, 2])).intValue, 1025);
     expect(Reference.fromBuffer(b([255, 255, 255, 127, 6, 4])).intValue,
-      2147483647);
+        2147483647);
+    expect(Reference.fromBuffer(b([0, 0, 0, 128, 6, 4])).intValue, -2147483648);
     expect(
-      Reference.fromBuffer(b([0, 0, 0, 128, 6, 4])).intValue, -2147483648);
+        Reference.fromBuffer(b([255, 255, 255, 255, 0, 0, 0, 0, 7, 8]))
+            .intValue,
+        4294967295);
     expect(
-      Reference.fromBuffer(b([255, 255, 255, 255, 0, 0, 0, 0, 7, 8]))
-        .intValue,
-      4294967295);
-    expect(
-      Reference.fromBuffer(b([255, 255, 255, 255, 255, 255, 255, 127, 7, 8]))
-        .intValue,
-      9223372036854775807);
+        Reference.fromBuffer(b([255, 255, 255, 255, 255, 255, 255, 127, 7, 8]))
+            .intValue,
+        9223372036854775807);
     expect(Reference.fromBuffer(b([0, 0, 0, 0, 0, 0, 0, 128, 7, 8])).intValue,
-      -9223372036854775808);
+        -9223372036854775808);
     // Dart does not really support UInt64
 //      expect(FlxValue.fromBuffer(b([255, 255, 255, 255, 255, 255, 255, 255, 11, 8])).intValue, 18446744073709551615);
   });
   test('double value', () {
     expect(Reference.fromBuffer(b([0, 0, 144, 64, 14, 4])).doubleValue, 4.5);
     expect(Reference.fromBuffer(b([205, 204, 204, 61, 14, 4])).doubleValue,
-      closeTo(.1, .001));
+        closeTo(.1, .001));
     expect(
-      Reference.fromBuffer(b([154, 153, 153, 153, 153, 153, 185, 63, 15, 8]))
-        .doubleValue,
-      .1);
+        Reference.fromBuffer(b([154, 153, 153, 153, 153, 153, 185, 63, 15, 8]))
+            .doubleValue,
+        .1);
   });
   test('num value', () {
     expect(Reference.fromBuffer(b([0, 0, 144, 64, 14, 4])).numValue, 4.5);
     expect(Reference.fromBuffer(b([205, 204, 204, 61, 14, 4])).numValue,
-      closeTo(.1, .001));
+        closeTo(.1, .001));
     expect(
-      Reference.fromBuffer(b([154, 153, 153, 153, 153, 153, 185, 63, 15, 8]))
-        .numValue,
-      .1);
+        Reference.fromBuffer(b([154, 153, 153, 153, 153, 153, 185, 63, 15, 8]))
+            .numValue,
+        .1);
     expect(Reference.fromBuffer(b([255, 251, 5, 2])).numValue, -1025);
   });
   test('string value', () {
     expect(
-      Reference.fromBuffer(b([5, 77, 97, 120, 105, 109, 0, 6, 20, 1]))
-        .stringValue,
-      'Maxim');
+        Reference.fromBuffer(b([5, 77, 97, 120, 105, 109, 0, 6, 20, 1]))
+            .stringValue,
+        'Maxim');
     expect(
-      Reference.fromBuffer(b([
-        10, 104, 101, 108, 108, 111, 32, 240, 159, 152, 177, 0, 11, 20, 1
-      ])).stringValue,
-      'hello 😱');
+        Reference.fromBuffer(b([
+          10,
+          104,
+          101,
+          108,
+          108,
+          111,
+          32,
+          240,
+          159,
+          152,
+          177,
+          0,
+          11,
+          20,
+          1
+        ])).stringValue,
+        'hello 😱');
   });
   test('blob value', () {
     expect(
-      Reference.fromBuffer(b([3, 1, 2, 3, 3, 100, 1])).blobValue, [1, 2, 3]);
+        Reference.fromBuffer(b([3, 1, 2, 3, 3, 100, 1])).blobValue, [1, 2, 3]);
   });
   test('bool vector', () {
     var flx = Reference.fromBuffer(b([3, 1, 0, 1, 3, 144, 1]));
@@ -81,27 +94,92 @@ void main() {
     testNumbers([3, 1, 2, 3, 3, 44, 1], [1, 2, 3]);
     testNumbers([3, 255, 2, 3, 3, 44, 1], [-1, 2, 3]);
     testNumbers([3, 0, 1, 0, 43, 2, 3, 0, 6, 45, 1], [1, 555, 3]);
-    testNumbers(
-      [3, 0, 0, 0, 1, 0, 0, 0, 204, 216, 0, 0, 3, 0, 0, 0, 12, 46, 1],
-      [1, 55500, 3]);
+    testNumbers([3, 0, 0, 0, 1, 0, 0, 0, 204, 216, 0, 0, 3, 0, 0, 0, 12, 46, 1],
+        [1, 55500, 3]);
     testNumbers([
-      3, 0, 0, 0, 0, 0, 0, 0,
-      1, 0, 0, 0, 0, 0, 0, 0,
-      172, 128, 94, 239, 12, 0, 0, 0,
-      3, 0, 0, 0, 0, 0, 0, 0,
-      24, 47, 1
-    ], [1, 55555555500, 3
+      3,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      1,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      172,
+      128,
+      94,
+      239,
+      12,
+      0,
+      0,
+      0,
+      3,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      24,
+      47,
+      1
+    ], [
+      1,
+      55555555500,
+      3
     ]);
     testNumbers(
-      [3, 0, 0, 0, 0, 0, 192, 63, 0, 0, 32, 64, 0, 0, 96, 64, 12, 54, 1],
-      [1.5, 2.5, 3.5]);
+        [3, 0, 0, 0, 0, 0, 192, 63, 0, 0, 32, 64, 0, 0, 96, 64, 12, 54, 1],
+        [1.5, 2.5, 3.5]);
     testNumbers([
-      3, 0, 0, 0, 0, 0, 0, 0,
-      154, 153, 153, 153, 153, 153, 241, 63,
-      154, 153, 153, 153, 153, 153, 1, 64,
-      102, 102, 102, 102, 102, 102, 10, 64,
-      24, 55, 1
-    ], [1.1, 2.2, 3.3
+      3,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      154,
+      153,
+      153,
+      153,
+      153,
+      153,
+      241,
+      63,
+      154,
+      153,
+      153,
+      153,
+      153,
+      153,
+      1,
+      64,
+      102,
+      102,
+      102,
+      102,
+      102,
+      102,
+      10,
+      64,
+      24,
+      55,
+      1
+    ], [
+      1.1,
+      2.2,
+      3.3
     ]);
   });
   test('number vector, fixed type', () {
@@ -109,11 +187,28 @@ void main() {
     testNumbers([255, 255, 0, 1, 4, 65, 1], [-1, 256]);
     testNumbers([211, 255, 255, 255, 0, 232, 3, 0, 8, 66, 1], [-45, 256000]);
     testNumbers([
-      211, 255, 255, 255, 255, 255, 255, 255,
-      255, 255, 255, 255, 255, 255, 255, 127,
-      16, 67, 1
+      211,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      127,
+      16,
+      67,
+      1
     ], [
-      -45, 9223372036854775807
+      -45,
+      9223372036854775807
     ]);
 
     testNumbers([1, 2, 2, 68, 1], [1, 2]);
@@ -122,85 +217,326 @@ void main() {
 
     testNumbers([205, 204, 140, 63, 0, 0, 0, 192, 8, 74, 1], [1.1, -2]);
     testNumbers([
-      154, 153, 153, 153, 153, 153, 241, 63,
-      0, 0, 0, 0, 0, 0, 112, 192,
-      16, 75, 1
+      154,
+      153,
+      153,
+      153,
+      153,
+      153,
+      241,
+      63,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      112,
+      192,
+      16,
+      75,
+      1
     ], [
-      1.1, -256
+      1.1,
+      -256
     ]);
 
     testNumbers([211, 255, 255, 255, 0, 232, 3, 0, 4, 0, 0, 0, 12, 78, 1],
-      [-45, 256000, 4]);
+        [-45, 256000, 4]);
 
     testNumbers([
-      211, 255, 255, 255, 255, 255, 255, 255,
-      255, 255, 255, 255, 255, 255, 255, 127,
-      4, 0, 0, 0, 0, 0, 0, 0,
-      9, 0, 0, 0, 0, 0, 0, 0,
-      32, 91, 1
+      211,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      127,
+      4,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      9,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      32,
+      91,
+      1
     ], [
-      -45, 9223372036854775807, 4, 9
+      -45,
+      9223372036854775807,
+      4,
+      9
     ]);
 
     testNumbers([
-      45, 0, 0, 0, 0, 0, 0, 0,
-      255, 255, 255, 255, 255, 255, 255, 127,
-      4, 0, 0, 0, 0, 0, 0, 0,
-      9, 0, 0, 0, 0, 0, 0, 0,
-      32, 95, 1
+      45,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      127,
+      4,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      9,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      32,
+      95,
+      1
     ], [
-      45, 9223372036854775807, 4, 9
+      45,
+      9223372036854775807,
+      4,
+      9
     ]);
 
     testNumbers([
-      154, 153, 153, 153, 153, 153, 241, 63,
-      0, 0, 0, 0, 0, 0, 112, 64,
-      0, 0, 0, 0, 0, 0, 16, 64,
-      24, 87, 1
+      154,
+      153,
+      153,
+      153,
+      153,
+      153,
+      241,
+      63,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      112,
+      64,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      16,
+      64,
+      24,
+      87,
+      1
     ], [
-      1.1, 256, 4
+      1.1,
+      256,
+      4
     ]);
 
     testNumbers([
-      154, 153, 153, 153, 153, 153, 241, 63,
-      0, 0, 0, 0, 0, 0, 112, 64,
-      0, 0, 0, 0, 0, 0, 16, 64,
-      0, 0, 0, 0, 0, 0, 34, 64,
-      32, 99, 1
+      154,
+      153,
+      153,
+      153,
+      153,
+      153,
+      241,
+      63,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      112,
+      64,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      16,
+      64,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      34,
+      64,
+      32,
+      99,
+      1
     ], [
-      1.1, 256, 4, 9
+      1.1,
+      256,
+      4,
+      9
     ]);
   });
   test('string vector', () {
     testStrings([
-      3, 102, 111, 111, 0,
-      3, 98, 97, 114, 0,
-      3, 98, 97, 122, 0,
-      3, 15, 11, 7,
-      3, 60, 1
+      3,
+      102,
+      111,
+      111,
+      0,
+      3,
+      98,
+      97,
+      114,
+      0,
+      3,
+      98,
+      97,
+      122,
+      0,
+      3,
+      15,
+      11,
+      7,
+      3,
+      60,
+      1
     ], [
-      'foo', 'bar', 'baz'
+      'foo',
+      'bar',
+      'baz'
     ]);
     testStrings([
-      3, 102, 111, 111, 0,
-      3, 98, 97, 114, 0,
-      3, 98, 97, 122, 0,
-      6, 15, 11, 7, 18, 14, 10,
-      6, 60, 1
+      3,
+      102,
+      111,
+      111,
+      0,
+      3,
+      98,
+      97,
+      114,
+      0,
+      3,
+      98,
+      97,
+      122,
+      0,
+      6,
+      15,
+      11,
+      7,
+      18,
+      14,
+      10,
+      6,
+      60,
+      1
     ], [
-      'foo', 'bar', 'baz', 'foo', 'bar', 'baz'
+      'foo',
+      'bar',
+      'baz',
+      'foo',
+      'bar',
+      'baz'
     ]);
   });
   test('mixed vector', () {
     var flx = Reference.fromBuffer(b([
-      3, 102, 111, 111, 0, 0, 0, 0,
-      5, 0, 0, 0, 0, 0, 0, 0,
-      15, 0, 0, 0, 0, 0, 0, 0,
-      1, 0, 0, 0, 0, 0, 0, 0,
-      251, 255, 255, 255, 255, 255, 255, 255,
-      205, 204, 204, 204, 204, 204, 244, 63,
-      1, 0, 0, 0, 0, 0, 0, 0,
-      20, 4, 4, 15, 104, 45, 43, 1
+      3,
+      102,
+      111,
+      111,
+      0,
+      0,
+      0,
+      0,
+      5,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      15,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      1,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      251,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      255,
+      205,
+      204,
+      204,
+      204,
+      204,
+      204,
+      244,
+      63,
+      1,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      0,
+      20,
+      4,
+      4,
+      15,
+      104,
+      45,
+      43,
+      1
     ]));
     expect(flx.length, 5);
     expect(flx[0].stringValue, 'foo');
@@ -216,7 +552,8 @@ void main() {
     expect(flx['a'].numValue, 12);
   });
   test('two value map', () {
-    var flx = Reference.fromBuffer(b([0, 97, 0, 2, 4, 4, 2, 1, 2, 45, 12, 4, 4, 4, 36, 1]));
+    var flx = Reference.fromBuffer(
+        b([0, 97, 0, 2, 4, 4, 2, 1, 2, 45, 12, 4, 4, 4, 36, 1]));
     expect(flx.length, 2);
     expect(flx['a'].numValue, 12);
     expect(flx[''].numValue, 45);
@@ -239,45 +576,239 @@ void main() {
     expect(flx['address']['zip'].stringValue, '12345');
     expect(flx['address']['countryCode'].stringValue, 'XX');
 
-    expect(() => flx['address']['country'].stringValue,
-      throwsA(predicate((e) => e is ArgumentError && e.message == 'Key: [country] is not applicable on: //address of: ValueType.Map')));
-    expect(() => flx['address']['countryCode'][0],
-      throwsA(predicate((e) => e is ArgumentError && e.message == 'Key: [0] is not applicable on: //address/countryCode of: ValueType.String')));
-    expect(() => flx[1],
-      throwsA(predicate((e) => e is ArgumentError && e.message == 'Key: [1] is not applicable on: / of: ValueType.Map')));
-    expect(() => flx['flags'][4],
-      throwsA(predicate((e) => e is ArgumentError && e.message == 'Key: [4] is not applicable on: //flags of: ValueType.VectorBool length: 4')));
-    expect(() => flx['flags'][-1],
-      throwsA(predicate((e) => e is ArgumentError && e.message == 'Key: [-1] is not applicable on: //flags of: ValueType.VectorBool length: 4')));
+    expect(
+        () => flx['address']['country'].stringValue,
+        throwsA(predicate((dynamic e) =>
+            e is ArgumentError &&
+            e.message ==
+                'Key: [country] is not applicable on: //address of: ValueType.Map')));
+    expect(
+        () => flx['address']['countryCode'][0],
+        throwsA(predicate((dynamic e) =>
+            e is ArgumentError &&
+            e.message ==
+                'Key: [0] is not applicable on: //address/countryCode of: ValueType.String')));
+    expect(
+        () => flx[1],
+        throwsA(predicate((dynamic e) =>
+            e is ArgumentError &&
+            e.message ==
+                'Key: [1] is not applicable on: / of: ValueType.Map')));
+    expect(
+        () => flx['flags'][4],
+        throwsA(predicate((dynamic e) =>
+            e is ArgumentError &&
+            e.message ==
+                'Key: [4] is not applicable on: //flags of: ValueType.VectorBool length: 4')));
+    expect(
+        () => flx['flags'][-1],
+        throwsA(predicate((dynamic e) =>
+            e is ArgumentError &&
+            e.message ==
+                'Key: [-1] is not applicable on: //flags of: ValueType.VectorBool length: 4')));
   });
   test('complex map to json', () {
     var flx = complexMap();
-    expect(flx.json, '{"address":{"city":"Bla","countryCode":"XX","zip":"12345"},"age":35,"flags":[true,false,true,true],"name":"Maxim","weight":72.5}');
+    expect(flx.json,
+        '{"address":{"city":"Bla","countryCode":"XX","zip":"12345"},"age":35,"flags":[true,false,true,true],"name":"Maxim","weight":72.5}');
   });
 
   test('complex map iterators', () {
     var flx = complexMap();
-    expect(flx.mapKeyIterable.map((e) => e).toList(), ['address', 'age', 'flags', 'name', 'weight']);
-    expect(flx.mapValueIterable.map((e) => e.json).toList(), [flx['address'].json, flx['age'].json, flx['flags'].json, flx['name'].json, flx['weight'].json]);
-    expect(flx['flags'].vectorIterable.map((e) => e.boolValue).toList(), [true, false, true, true]);
+    expect(flx.mapKeyIterable.map((e) => e).toList(),
+        ['address', 'age', 'flags', 'name', 'weight']);
+    expect(flx.mapValueIterable.map((e) => e.json).toList(), [
+      flx['address'].json,
+      flx['age'].json,
+      flx['flags'].json,
+      flx['name'].json,
+      flx['weight'].json
+    ]);
+    expect(flx['flags'].vectorIterable.map((e) => e.boolValue).toList(),
+        [true, false, true, true]);
   });
 
-  test('bug where offest were stored as int instead of uint', (){
-    const data = [99, 104, 97, 110, 110, 101, 108, 115, 95, 105, 110, 0,
-      100, 105, 108, 97, 116, 105, 111, 110, 95, 104, 101, 105, 103, 104, 116, 95, 102, 97, 99, 116, 111, 114, 0,
-      100, 105, 108, 97, 116, 105, 111, 110, 95, 119, 105, 100, 116, 104, 95, 102, 97, 99, 116, 111, 114, 0,
-      102, 117, 115, 101, 100, 95, 97, 99, 116, 105, 118, 97, 116, 105, 111, 110, 95, 102, 117, 110, 99, 116, 105, 111, 110, 0,
-      112, 97, 100, 95, 118, 97, 108, 117, 101, 115, 0, 112, 97, 100, 100, 105, 110, 103, 0,
-      115, 116, 114, 105, 100, 101, 95, 104, 101, 105, 103, 104, 116, 0,
-      115, 116, 114, 105, 100, 101, 95, 119, 105, 100, 116, 104, 0,
-      8, 130, 119, 97, 76, 51, 41, 34, 21, 8, 1, 8, 64, 1, 1, 1, 1, 0, 1, 1, 4, 4, 4, 4, 4, 4, 4, 4, 16, 36, 1];
+  test('bug where offest were stored as int instead of uint', () {
+    const data = [
+      99,
+      104,
+      97,
+      110,
+      110,
+      101,
+      108,
+      115,
+      95,
+      105,
+      110,
+      0,
+      100,
+      105,
+      108,
+      97,
+      116,
+      105,
+      111,
+      110,
+      95,
+      104,
+      101,
+      105,
+      103,
+      104,
+      116,
+      95,
+      102,
+      97,
+      99,
+      116,
+      111,
+      114,
+      0,
+      100,
+      105,
+      108,
+      97,
+      116,
+      105,
+      111,
+      110,
+      95,
+      119,
+      105,
+      100,
+      116,
+      104,
+      95,
+      102,
+      97,
+      99,
+      116,
+      111,
+      114,
+      0,
+      102,
+      117,
+      115,
+      101,
+      100,
+      95,
+      97,
+      99,
+      116,
+      105,
+      118,
+      97,
+      116,
+      105,
+      111,
+      110,
+      95,
+      102,
+      117,
+      110,
+      99,
+      116,
+      105,
+      111,
+      110,
+      0,
+      112,
+      97,
+      100,
+      95,
+      118,
+      97,
+      108,
+      117,
+      101,
+      115,
+      0,
+      112,
+      97,
+      100,
+      100,
+      105,
+      110,
+      103,
+      0,
+      115,
+      116,
+      114,
+      105,
+      100,
+      101,
+      95,
+      104,
+      101,
+      105,
+      103,
+      104,
+      116,
+      0,
+      115,
+      116,
+      114,
+      105,
+      100,
+      101,
+      95,
+      119,
+      105,
+      100,
+      116,
+      104,
+      0,
+      8,
+      130,
+      119,
+      97,
+      76,
+      51,
+      41,
+      34,
+      21,
+      8,
+      1,
+      8,
+      64,
+      1,
+      1,
+      1,
+      1,
+      0,
+      1,
+      1,
+      4,
+      4,
+      4,
+      4,
+      4,
+      4,
+      4,
+      4,
+      16,
+      36,
+      1
+    ];
     var flx = Reference.fromBuffer(b(data));
-    expect(flx.json, '{"channels_in":64,"dilation_height_factor":1,"dilation_width_factor":1,"fused_activation_function":1,"pad_values":1,"padding":0,"stride_height":1,"stride_width":1}');
-    const object = {"channels_in":64,"dilation_height_factor":1,"dilation_width_factor":1,"fused_activation_function":1,"pad_values":1,"padding":0,"stride_height":1,"stride_width":1};
+    expect(flx.json,
+        '{"channels_in":64,"dilation_height_factor":1,"dilation_width_factor":1,"fused_activation_function":1,"pad_values":1,"padding":0,"stride_height":1,"stride_width":1}');
+    const object = {
+      "channels_in": 64,
+      "dilation_height_factor": 1,
+      "dilation_width_factor": 1,
+      "fused_activation_function": 1,
+      "pad_values": 1,
+      "padding": 0,
+      "stride_height": 1,
+      "stride_width": 1
+    };
     var data1 = Builder.buildFromObject(object).asUint8List();
     expect(data1.length, data.length);
     var flx1 = Reference.fromBuffer(b(data1));
-    expect(flx1.json, '{"channels_in":64,"dilation_height_factor":1,"dilation_width_factor":1,"fused_activation_function":1,"pad_values":1,"padding":0,"stride_height":1,"stride_width":1}');
+    expect(flx1.json,
+        '{"channels_in":64,"dilation_height_factor":1,"dilation_width_factor":1,"fused_activation_function":1,"pad_values":1,"padding":0,"stride_height":1,"stride_width":1}');
   });
 }
 
@@ -302,7 +833,7 @@ void testStrings(List<int> buffer, List<String> numbers) {
   }
 }
 
-Reference complexMap(){
+Reference complexMap() {
 //  {
 //    "age": 35,
 //    "flags": [True, False, True, True],
@@ -315,20 +846,145 @@ Reference complexMap(){
 //    }
 //  }
   return Reference.fromBuffer(b([
-  97, 100, 100, 114, 101, 115, 115, 0,
-      99, 105, 116, 121, 0, 3, 66, 108, 97, 0,
-      99, 111, 117, 110, 116, 114, 121, 67, 111, 100, 101, 0,
-      2, 88, 88, 0,
-      122, 105, 112, 0,
-      5, 49, 50, 51, 52, 53, 0,
-      3, 38, 29, 14, 3, 1, 3, 38, 22, 15, 20, 20, 20,
-      97, 103, 101, 0,
-      102, 108, 97, 103, 115, 0,
-      4, 1, 0, 1, 1,
-      110, 97, 109, 101, 0,
-      5, 77, 97, 120, 105, 109, 0,
-      119, 101, 105, 103, 104, 116, 0,
-      5, 93, 36, 33, 23, 12, 0, 0, 7, 0, 0, 0, 1, 0, 0, 0, 5, 0, 0, 0, 60, 0, 0, 0, 35, 0, 0, 0, 51, 0, 0, 0, 45,
-      0, 0, 0, 0, 0, 145, 66, 36, 4, 144, 20, 14, 25, 38, 1
+    97,
+    100,
+    100,
+    114,
+    101,
+    115,
+    115,
+    0,
+    99,
+    105,
+    116,
+    121,
+    0,
+    3,
+    66,
+    108,
+    97,
+    0,
+    99,
+    111,
+    117,
+    110,
+    116,
+    114,
+    121,
+    67,
+    111,
+    100,
+    101,
+    0,
+    2,
+    88,
+    88,
+    0,
+    122,
+    105,
+    112,
+    0,
+    5,
+    49,
+    50,
+    51,
+    52,
+    53,
+    0,
+    3,
+    38,
+    29,
+    14,
+    3,
+    1,
+    3,
+    38,
+    22,
+    15,
+    20,
+    20,
+    20,
+    97,
+    103,
+    101,
+    0,
+    102,
+    108,
+    97,
+    103,
+    115,
+    0,
+    4,
+    1,
+    0,
+    1,
+    1,
+    110,
+    97,
+    109,
+    101,
+    0,
+    5,
+    77,
+    97,
+    120,
+    105,
+    109,
+    0,
+    119,
+    101,
+    105,
+    103,
+    104,
+    116,
+    0,
+    5,
+    93,
+    36,
+    33,
+    23,
+    12,
+    0,
+    0,
+    7,
+    0,
+    0,
+    0,
+    1,
+    0,
+    0,
+    0,
+    5,
+    0,
+    0,
+    0,
+    60,
+    0,
+    0,
+    0,
+    35,
+    0,
+    0,
+    0,
+    51,
+    0,
+    0,
+    0,
+    45,
+    0,
+    0,
+    0,
+    0,
+    0,
+    145,
+    66,
+    36,
+    4,
+    144,
+    20,
+    14,
+    25,
+    38,
+    1
   ]));
 }
diff --git a/dart/test/flex_types_test.dart b/dart/test/flex_types_test.dart
index 16235f62..76ce0704 100644
--- a/dart/test/flex_types_test.dart
+++ b/dart/test/flex_types_test.dart
@@ -48,69 +48,116 @@ void main() {
     expect(ValueTypeUtils.isFixedTypedVector(ValueType.VectorInt), isFalse);
   });
   test('to typed vector', () {
-    expect(ValueTypeUtils.toTypedVector(ValueType.Int,0), equals(ValueType.VectorInt));
-    expect(ValueTypeUtils.toTypedVector(ValueType.UInt,0), equals(ValueType.VectorUInt));
-    expect(ValueTypeUtils.toTypedVector(ValueType.Bool,0), equals(ValueType.VectorBool));
-    expect(ValueTypeUtils.toTypedVector(ValueType.Float,0), equals(ValueType.VectorFloat));
-    expect(ValueTypeUtils.toTypedVector(ValueType.Key,0), equals(ValueType.VectorKey));
-    expect(ValueTypeUtils.toTypedVector(ValueType.String,0), equals(ValueType.VectorString));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Int, 0),
+        equals(ValueType.VectorInt));
+    expect(ValueTypeUtils.toTypedVector(ValueType.UInt, 0),
+        equals(ValueType.VectorUInt));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Bool, 0),
+        equals(ValueType.VectorBool));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Float, 0),
+        equals(ValueType.VectorFloat));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Key, 0),
+        equals(ValueType.VectorKey));
+    expect(ValueTypeUtils.toTypedVector(ValueType.String, 0),
+        equals(ValueType.VectorString));
 
-    expect(ValueTypeUtils.toTypedVector(ValueType.Int,2), equals(ValueType.VectorInt2));
-    expect(ValueTypeUtils.toTypedVector(ValueType.UInt,2), equals(ValueType.VectorUInt2));
-    expect(ValueTypeUtils.toTypedVector(ValueType.Float,2), equals(ValueType.VectorFloat2));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Int, 2),
+        equals(ValueType.VectorInt2));
+    expect(ValueTypeUtils.toTypedVector(ValueType.UInt, 2),
+        equals(ValueType.VectorUInt2));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Float, 2),
+        equals(ValueType.VectorFloat2));
 
-    expect(ValueTypeUtils.toTypedVector(ValueType.Int,3), equals(ValueType.VectorInt3));
-    expect(ValueTypeUtils.toTypedVector(ValueType.UInt,3), equals(ValueType.VectorUInt3));
-    expect(ValueTypeUtils.toTypedVector(ValueType.Float,3), equals(ValueType.VectorFloat3));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Int, 3),
+        equals(ValueType.VectorInt3));
+    expect(ValueTypeUtils.toTypedVector(ValueType.UInt, 3),
+        equals(ValueType.VectorUInt3));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Float, 3),
+        equals(ValueType.VectorFloat3));
 
-    expect(ValueTypeUtils.toTypedVector(ValueType.Int,4), equals(ValueType.VectorInt4));
-    expect(ValueTypeUtils.toTypedVector(ValueType.UInt,4), equals(ValueType.VectorUInt4));
-    expect(ValueTypeUtils.toTypedVector(ValueType.Float,4), equals(ValueType.VectorFloat4));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Int, 4),
+        equals(ValueType.VectorInt4));
+    expect(ValueTypeUtils.toTypedVector(ValueType.UInt, 4),
+        equals(ValueType.VectorUInt4));
+    expect(ValueTypeUtils.toTypedVector(ValueType.Float, 4),
+        equals(ValueType.VectorFloat4));
   });
   test('typed vector element type', () {
-    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorInt), equals(ValueType.Int));
-    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorUInt), equals(ValueType.UInt));
-    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorFloat), equals(ValueType.Float));
-    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorString), equals(ValueType.String));
-    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorKey), equals(ValueType.Key));
-    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorBool), equals(ValueType.Bool));
+    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorInt),
+        equals(ValueType.Int));
+    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorUInt),
+        equals(ValueType.UInt));
+    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorFloat),
+        equals(ValueType.Float));
+    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorString),
+        equals(ValueType.String));
+    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorKey),
+        equals(ValueType.Key));
+    expect(ValueTypeUtils.typedVectorElementType(ValueType.VectorBool),
+        equals(ValueType.Bool));
   });
   test('fixed typed vector element type', () {
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorInt2), equals(ValueType.Int));
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorInt3), equals(ValueType.Int));
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorInt4), equals(ValueType.Int));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorInt2),
+        equals(ValueType.Int));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorInt3),
+        equals(ValueType.Int));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorInt4),
+        equals(ValueType.Int));
 
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorUInt2), equals(ValueType.UInt));
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorUInt3), equals(ValueType.UInt));
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorUInt4), equals(ValueType.UInt));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorUInt2),
+        equals(ValueType.UInt));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorUInt3),
+        equals(ValueType.UInt));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorUInt4),
+        equals(ValueType.UInt));
 
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorFloat2), equals(ValueType.Float));
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorFloat3), equals(ValueType.Float));
-    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorFloat4), equals(ValueType.Float));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorFloat2),
+        equals(ValueType.Float));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorFloat3),
+        equals(ValueType.Float));
+    expect(ValueTypeUtils.fixedTypedVectorElementType(ValueType.VectorFloat4),
+        equals(ValueType.Float));
   });
   test('fixed typed vector element size', () {
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorInt2), equals(2));
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorInt3), equals(3));
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorInt4), equals(4));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorInt2),
+        equals(2));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorInt3),
+        equals(3));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorInt4),
+        equals(4));
 
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorUInt2), equals(2));
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorUInt3), equals(3));
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorUInt4), equals(4));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorUInt2),
+        equals(2));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorUInt3),
+        equals(3));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorUInt4),
+        equals(4));
 
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorFloat2), equals(2));
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorFloat3), equals(3));
-    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorFloat4), equals(4));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorFloat2),
+        equals(2));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorFloat3),
+        equals(3));
+    expect(ValueTypeUtils.fixedTypedVectorElementSize(ValueType.VectorFloat4),
+        equals(4));
   });
   test('packed type', () {
-    expect(ValueTypeUtils.packedType(ValueType.Null, BitWidth.width8), equals(0));
-    expect(ValueTypeUtils.packedType(ValueType.Null, BitWidth.width16), equals(1));
-    expect(ValueTypeUtils.packedType(ValueType.Null, BitWidth.width32), equals(2));
-    expect(ValueTypeUtils.packedType(ValueType.Null, BitWidth.width64), equals(3));
+    expect(
+        ValueTypeUtils.packedType(ValueType.Null, BitWidth.width8), equals(0));
+    expect(
+        ValueTypeUtils.packedType(ValueType.Null, BitWidth.width16), equals(1));
+    expect(
+        ValueTypeUtils.packedType(ValueType.Null, BitWidth.width32), equals(2));
+    expect(
+        ValueTypeUtils.packedType(ValueType.Null, BitWidth.width64), equals(3));
 
-    expect(ValueTypeUtils.packedType(ValueType.Int, BitWidth.width8), equals(4));
-    expect(ValueTypeUtils.packedType(ValueType.Int, BitWidth.width16), equals(5));
-    expect(ValueTypeUtils.packedType(ValueType.Int, BitWidth.width32), equals(6));
-    expect(ValueTypeUtils.packedType(ValueType.Int, BitWidth.width64), equals(7));
+    expect(
+        ValueTypeUtils.packedType(ValueType.Int, BitWidth.width8), equals(4));
+    expect(
+        ValueTypeUtils.packedType(ValueType.Int, BitWidth.width16), equals(5));
+    expect(
+        ValueTypeUtils.packedType(ValueType.Int, BitWidth.width32), equals(6));
+    expect(
+        ValueTypeUtils.packedType(ValueType.Int, BitWidth.width64), equals(7));
   });
   test('bit width', () {
     expect(BitWidthUtil.width(0), BitWidth.width8);
diff --git a/dart/test/monster_test_my_game.example2_generated.dart b/dart/test/monster_test_my_game.example2_generated.dart
index d1c6a03a..92d7c911 100644
--- a/dart/test/monster_test_my_game.example2_generated.dart
+++ b/dart/test/monster_test_my_game.example2_generated.dart
@@ -1,5 +1,5 @@
 // automatically generated by the FlatBuffers compiler, do not modify
-// ignore_for_file: unused_import, unused_field, unused_local_variable
+// ignore_for_file: unused_import, unused_field, unused_element, unused_local_variable
 
 library my_game.example2;
 
@@ -29,7 +29,7 @@ class Monster {
 
   MonsterT unpack() => MonsterT();
 
-  static int pack(fb.Builder fbBuilder, MonsterT object) {
+  static int pack(fb.Builder fbBuilder, MonsterT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -37,8 +37,6 @@ class Monster {
 
 class MonsterT {
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
     fbBuilder.startTable();
     return fbBuilder.endTable();
   }
@@ -63,17 +61,14 @@ class MonsterObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     fbBuilder.startTable();
     return fbBuilder.endTable();
   }
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
diff --git a/dart/test/monster_test_my_game.example_generated.dart b/dart/test/monster_test_my_game.example_generated.dart
index 75302f9f..36ada7d5 100644
--- a/dart/test/monster_test_my_game.example_generated.dart
+++ b/dart/test/monster_test_my_game.example_generated.dart
@@ -1,5 +1,5 @@
 // automatically generated by the FlatBuffers compiler, do not modify
-// ignore_for_file: unused_import, unused_field, unused_local_variable
+// ignore_for_file: unused_import, unused_field, unused_element, unused_local_variable
 
 library my_game.example;
 
@@ -15,13 +15,16 @@ class Color {
   const Color._(this.value);
 
   factory Color.fromValue(int value) {
-    if (value == null) value = 0;
-    if (!values.containsKey(value)) {
+    final result = values[value];
+    if (result == null) {
       throw new StateError('Invalid value $value for bit flag enum Color');
     }
-    return values[value];
+    return result;
   }
 
+  static Color? _createOrNull(int? value) => 
+      value == null ? null : Color.fromValue(value);
+
   static bool containsValue(int value) => values.containsKey(value);
 
   static const Color Red = const Color._(1);
@@ -32,7 +35,10 @@ class Color {
 
   ///  \brief color Blue (1u << 3)
   static const Color Blue = const Color._(8);
-  static const Map<int,Color> values = {1: Red,2: Green,8: Blue,};
+  static const Map<int, Color> values = {
+    1: Red,
+    2: Green,
+    8: Blue};
 
   static const fb.Reader<Color> reader = const _ColorReader();
 
@@ -58,13 +64,16 @@ class Race {
   const Race._(this.value);
 
   factory Race.fromValue(int value) {
-    if (value == null) value = 0;
-    if (!values.containsKey(value)) {
+    final result = values[value];
+    if (result == null) {
       throw new StateError('Invalid value $value for bit flag enum Race');
     }
-    return values[value];
+    return result;
   }
 
+  static Race? _createOrNull(int? value) => 
+      value == null ? null : Race.fromValue(value);
+
   static const int minValue = -1;
   static const int maxValue = 2;
   static bool containsValue(int value) => values.containsKey(value);
@@ -73,7 +82,11 @@ class Race {
   static const Race Human = const Race._(0);
   static const Race Dwarf = const Race._(1);
   static const Race Elf = const Race._(2);
-  static const Map<int,Race> values = {-1: None,0: Human,1: Dwarf,2: Elf,};
+  static const Map<int, Race> values = {
+    -1: None,
+    0: Human,
+    1: Dwarf,
+    2: Elf};
 
   static const fb.Reader<Race> reader = const _RaceReader();
 
@@ -99,13 +112,16 @@ class AnyTypeId {
   const AnyTypeId._(this.value);
 
   factory AnyTypeId.fromValue(int value) {
-    if (value == null) value = 0;
-    if (!values.containsKey(value)) {
+    final result = values[value];
+    if (result == null) {
       throw new StateError('Invalid value $value for bit flag enum AnyTypeId');
     }
-    return values[value];
+    return result;
   }
 
+  static AnyTypeId? _createOrNull(int? value) => 
+      value == null ? null : AnyTypeId.fromValue(value);
+
   static const int minValue = 0;
   static const int maxValue = 3;
   static bool containsValue(int value) => values.containsKey(value);
@@ -114,7 +130,11 @@ class AnyTypeId {
   static const AnyTypeId Monster = const AnyTypeId._(1);
   static const AnyTypeId TestSimpleTableWithEnum = const AnyTypeId._(2);
   static const AnyTypeId MyGame_Example2_Monster = const AnyTypeId._(3);
-  static const Map<int,AnyTypeId> values = {0: NONE,1: Monster,2: TestSimpleTableWithEnum,3: MyGame_Example2_Monster,};
+  static const Map<int, AnyTypeId> values = {
+    0: NONE,
+    1: Monster,
+    2: TestSimpleTableWithEnum,
+    3: MyGame_Example2_Monster};
 
   static const fb.Reader<AnyTypeId> reader = const _AnyTypeIdReader();
 
@@ -140,13 +160,16 @@ class AnyUniqueAliasesTypeId {
   const AnyUniqueAliasesTypeId._(this.value);
 
   factory AnyUniqueAliasesTypeId.fromValue(int value) {
-    if (value == null) value = 0;
-    if (!values.containsKey(value)) {
+    final result = values[value];
+    if (result == null) {
       throw new StateError('Invalid value $value for bit flag enum AnyUniqueAliasesTypeId');
     }
-    return values[value];
+    return result;
   }
 
+  static AnyUniqueAliasesTypeId? _createOrNull(int? value) => 
+      value == null ? null : AnyUniqueAliasesTypeId.fromValue(value);
+
   static const int minValue = 0;
   static const int maxValue = 3;
   static bool containsValue(int value) => values.containsKey(value);
@@ -155,7 +178,11 @@ class AnyUniqueAliasesTypeId {
   static const AnyUniqueAliasesTypeId M = const AnyUniqueAliasesTypeId._(1);
   static const AnyUniqueAliasesTypeId TS = const AnyUniqueAliasesTypeId._(2);
   static const AnyUniqueAliasesTypeId M2 = const AnyUniqueAliasesTypeId._(3);
-  static const Map<int,AnyUniqueAliasesTypeId> values = {0: NONE,1: M,2: TS,3: M2,};
+  static const Map<int, AnyUniqueAliasesTypeId> values = {
+    0: NONE,
+    1: M,
+    2: TS,
+    3: M2};
 
   static const fb.Reader<AnyUniqueAliasesTypeId> reader = const _AnyUniqueAliasesTypeIdReader();
 
@@ -181,13 +208,16 @@ class AnyAmbiguousAliasesTypeId {
   const AnyAmbiguousAliasesTypeId._(this.value);
 
   factory AnyAmbiguousAliasesTypeId.fromValue(int value) {
-    if (value == null) value = 0;
-    if (!values.containsKey(value)) {
+    final result = values[value];
+    if (result == null) {
       throw new StateError('Invalid value $value for bit flag enum AnyAmbiguousAliasesTypeId');
     }
-    return values[value];
+    return result;
   }
 
+  static AnyAmbiguousAliasesTypeId? _createOrNull(int? value) => 
+      value == null ? null : AnyAmbiguousAliasesTypeId.fromValue(value);
+
   static const int minValue = 0;
   static const int maxValue = 3;
   static bool containsValue(int value) => values.containsKey(value);
@@ -196,7 +226,11 @@ class AnyAmbiguousAliasesTypeId {
   static const AnyAmbiguousAliasesTypeId M1 = const AnyAmbiguousAliasesTypeId._(1);
   static const AnyAmbiguousAliasesTypeId M2 = const AnyAmbiguousAliasesTypeId._(2);
   static const AnyAmbiguousAliasesTypeId M3 = const AnyAmbiguousAliasesTypeId._(3);
-  static const Map<int,AnyAmbiguousAliasesTypeId> values = {0: NONE,1: M1,2: M2,3: M3,};
+  static const Map<int, AnyAmbiguousAliasesTypeId> values = {
+    0: NONE,
+    1: M1,
+    2: M2,
+    3: M3};
 
   static const fb.Reader<AnyAmbiguousAliasesTypeId> reader = const _AnyAmbiguousAliasesTypeIdReader();
 
@@ -237,7 +271,7 @@ class Test {
       a: a,
       b: b);
 
-  static int pack(fb.Builder fbBuilder, TestT object) {
+  static int pack(fb.Builder fbBuilder, TestT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -248,12 +282,10 @@ class TestT {
   int b;
 
   TestT({
-      this.a,
-      this.b});
+      required this.a,
+      required this.b});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
     fbBuilder.pad(1);
     fbBuilder.putInt8(b);
     fbBuilder.putInt16(a);
@@ -278,9 +310,7 @@ class _TestReader extends fb.StructReader<Test> {
 }
 
 class TestBuilder {
-  TestBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  TestBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -298,18 +328,15 @@ class TestObjectBuilder extends fb.ObjectBuilder {
   final int _b;
 
   TestObjectBuilder({
-    int a,
-    int b,
+    required int a,
+    required int b,
   })
       : _a = a,
         _b = b;
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     fbBuilder.pad(1);
     fbBuilder.putInt8(_b);
     fbBuilder.putInt16(_a);
@@ -318,7 +345,7 @@ class TestObjectBuilder extends fb.ObjectBuilder {
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -336,7 +363,7 @@ class TestSimpleTableWithEnum {
   final fb.BufferContext _bc;
   final int _bcOffset;
 
-  Color get color => new Color.fromValue(const fb.Uint8Reader().vTableGet(_bc, _bcOffset, 4, 2));
+  Color get color => Color.fromValue(const fb.Uint8Reader().vTableGet(_bc, _bcOffset, 4, 2));
 
   @override
   String toString() {
@@ -346,7 +373,7 @@ class TestSimpleTableWithEnum {
   TestSimpleTableWithEnumT unpack() => TestSimpleTableWithEnumT(
       color: color);
 
-  static int pack(fb.Builder fbBuilder, TestSimpleTableWithEnumT object) {
+  static int pack(fb.Builder fbBuilder, TestSimpleTableWithEnumT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -356,13 +383,11 @@ class TestSimpleTableWithEnumT {
   Color color;
 
   TestSimpleTableWithEnumT({
-      this.color});
+      this.color = Color.Green});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
     fbBuilder.startTable();
-    fbBuilder.addUint8(0, color?.value);
+    fbBuilder.addUint8(0, color.value);
     return fbBuilder.endTable();
   }
 
@@ -381,9 +406,7 @@ class _TestSimpleTableWithEnumReader extends fb.TableReader<TestSimpleTableWithE
 }
 
 class TestSimpleTableWithEnumBuilder {
-  TestSimpleTableWithEnumBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  TestSimpleTableWithEnumBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -391,7 +414,7 @@ class TestSimpleTableWithEnumBuilder {
     fbBuilder.startTable();
   }
 
-  int addColor(Color color) {
+  int addColor(Color? color) {
     fbBuilder.addUint8(0, color?.value);
     return fbBuilder.offset;
   }
@@ -402,19 +425,16 @@ class TestSimpleTableWithEnumBuilder {
 }
 
 class TestSimpleTableWithEnumObjectBuilder extends fb.ObjectBuilder {
-  final Color _color;
+  final Color? _color;
 
   TestSimpleTableWithEnumObjectBuilder({
-    Color color,
+    Color? color,
   })
       : _color = color;
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     fbBuilder.startTable();
     fbBuilder.addUint8(0, _color?.value);
     return fbBuilder.endTable();
@@ -422,7 +442,7 @@ class TestSimpleTableWithEnumObjectBuilder extends fb.ObjectBuilder {
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -440,7 +460,7 @@ class Vec3 {
   double get y => const fb.Float32Reader().read(_bc, _bcOffset + 4);
   double get z => const fb.Float32Reader().read(_bc, _bcOffset + 8);
   double get test1 => const fb.Float64Reader().read(_bc, _bcOffset + 16);
-  Color get test2 => new Color.fromValue(const fb.Uint8Reader().read(_bc, _bcOffset + 24));
+  Color get test2 => Color.fromValue(const fb.Uint8Reader().read(_bc, _bcOffset + 24));
   Test get test3 => Test.reader.read(_bc, _bcOffset + 26);
 
   @override
@@ -454,9 +474,9 @@ class Vec3 {
       z: z,
       test1: test1,
       test2: test2,
-      test3: test3?.unpack());
+      test3: test3.unpack());
 
-  static int pack(fb.Builder fbBuilder, Vec3T object) {
+  static int pack(fb.Builder fbBuilder, Vec3T? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -471,20 +491,18 @@ class Vec3T {
   TestT test3;
 
   Vec3T({
-      this.x,
-      this.y,
-      this.z,
-      this.test1,
-      this.test2,
-      this.test3});
+      required this.x,
+      required this.y,
+      required this.z,
+      required this.test1,
+      required this.test2,
+      required this.test3});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
     fbBuilder.pad(2);
     test3.pack(fbBuilder);
     fbBuilder.pad(1);
-    fbBuilder.putUint8(test2?.value);
+    fbBuilder.putUint8(test2.value);
     fbBuilder.putFloat64(test1);
     fbBuilder.pad(4);
     fbBuilder.putFloat32(z);
@@ -511,9 +529,7 @@ class _Vec3Reader extends fb.StructReader<Vec3> {
 }
 
 class Vec3Builder {
-  Vec3Builder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  Vec3Builder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -521,7 +537,7 @@ class Vec3Builder {
     fbBuilder.pad(2);
     test3();
     fbBuilder.pad(1);
-    fbBuilder.putUint8(test2?.value);
+    fbBuilder.putUint8(test2.value);
     fbBuilder.putFloat64(test1);
     fbBuilder.pad(4);
     fbBuilder.putFloat32(z);
@@ -541,12 +557,12 @@ class Vec3ObjectBuilder extends fb.ObjectBuilder {
   final TestObjectBuilder _test3;
 
   Vec3ObjectBuilder({
-    double x,
-    double y,
-    double z,
-    double test1,
-    Color test2,
-    TestObjectBuilder test3,
+    required double x,
+    required double y,
+    required double z,
+    required double test1,
+    required Color test2,
+    required TestObjectBuilder test3,
   })
       : _x = x,
         _y = y,
@@ -557,14 +573,11 @@ class Vec3ObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     fbBuilder.pad(2);
     _test3.finish(fbBuilder);
     fbBuilder.pad(1);
-    fbBuilder.putUint8(_test2?.value);
+    fbBuilder.putUint8(_test2.value);
     fbBuilder.putFloat64(_test1);
     fbBuilder.pad(4);
     fbBuilder.putFloat32(_z);
@@ -575,7 +588,7 @@ class Vec3ObjectBuilder extends fb.ObjectBuilder {
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -601,7 +614,7 @@ class Ability {
       id: id,
       distance: distance);
 
-  static int pack(fb.Builder fbBuilder, AbilityT object) {
+  static int pack(fb.Builder fbBuilder, AbilityT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -612,12 +625,10 @@ class AbilityT {
   int distance;
 
   AbilityT({
-      this.id,
-      this.distance});
+      required this.id,
+      required this.distance});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
     fbBuilder.putUint32(distance);
     fbBuilder.putUint32(id);
     return fbBuilder.offset;
@@ -641,9 +652,7 @@ class _AbilityReader extends fb.StructReader<Ability> {
 }
 
 class AbilityBuilder {
-  AbilityBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  AbilityBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -660,18 +669,15 @@ class AbilityObjectBuilder extends fb.ObjectBuilder {
   final int _distance;
 
   AbilityObjectBuilder({
-    int id,
-    int distance,
+    required int id,
+    required int distance,
   })
       : _id = id,
         _distance = distance;
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     fbBuilder.putUint32(_distance);
     fbBuilder.putUint32(_id);
     return fbBuilder.offset;
@@ -679,7 +685,7 @@ class AbilityObjectBuilder extends fb.ObjectBuilder {
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -703,11 +709,11 @@ class StructOfStructs {
   }
 
   StructOfStructsT unpack() => StructOfStructsT(
-      a: a?.unpack(),
-      b: b?.unpack(),
-      c: c?.unpack());
+      a: a.unpack(),
+      b: b.unpack(),
+      c: c.unpack());
 
-  static int pack(fb.Builder fbBuilder, StructOfStructsT object) {
+  static int pack(fb.Builder fbBuilder, StructOfStructsT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -719,13 +725,11 @@ class StructOfStructsT {
   AbilityT c;
 
   StructOfStructsT({
-      this.a,
-      this.b,
-      this.c});
+      required this.a,
+      required this.b,
+      required this.c});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
     c.pack(fbBuilder);
     b.pack(fbBuilder);
     a.pack(fbBuilder);
@@ -750,9 +754,7 @@ class _StructOfStructsReader extends fb.StructReader<StructOfStructs> {
 }
 
 class StructOfStructsBuilder {
-  StructOfStructsBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  StructOfStructsBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -771,9 +773,9 @@ class StructOfStructsObjectBuilder extends fb.ObjectBuilder {
   final AbilityObjectBuilder _c;
 
   StructOfStructsObjectBuilder({
-    AbilityObjectBuilder a,
-    TestObjectBuilder b,
-    AbilityObjectBuilder c,
+    required AbilityObjectBuilder a,
+    required TestObjectBuilder b,
+    required AbilityObjectBuilder c,
   })
       : _a = a,
         _b = b,
@@ -781,10 +783,7 @@ class StructOfStructsObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     _c.finish(fbBuilder);
     _b.finish(fbBuilder);
     _a.finish(fbBuilder);
@@ -793,7 +792,7 @@ class StructOfStructsObjectBuilder extends fb.ObjectBuilder {
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -811,7 +810,7 @@ class Stat {
   final fb.BufferContext _bc;
   final int _bcOffset;
 
-  String get id => const fb.StringReader().vTableGet(_bc, _bcOffset, 4, null);
+  String? get id => const fb.StringReader().vTableGetNullable(_bc, _bcOffset, 4);
   int get val => const fb.Int64Reader().vTableGet(_bc, _bcOffset, 6, 0);
   int get count => const fb.Uint16Reader().vTableGet(_bc, _bcOffset, 8, 0);
 
@@ -825,30 +824,26 @@ class Stat {
       val: val,
       count: count);
 
-  static int pack(fb.Builder fbBuilder, StatT object) {
+  static int pack(fb.Builder fbBuilder, StatT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
 }
 
 class StatT {
-  String id;
+  String? id;
   int val;
   int count;
 
   StatT({
       this.id,
-      this.val,
-      this.count});
+      this.val = 0,
+      this.count = 0});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-    final int idOffset = fbBuilder.writeString(id);
-
+    final int? idOffset = fbBuilder.writeString(id);
     fbBuilder.startTable();
-    if (idOffset != null) {
-      fbBuilder.addOffset(0, idOffset);
-    }
+    fbBuilder.addOffset(0, idOffset);
     fbBuilder.addInt64(1, val);
     fbBuilder.addUint16(2, count);
     return fbBuilder.endTable();
@@ -869,9 +864,7 @@ class _StatReader extends fb.TableReader<Stat> {
 }
 
 class StatBuilder {
-  StatBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  StatBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -879,15 +872,15 @@ class StatBuilder {
     fbBuilder.startTable();
   }
 
-  int addIdOffset(int offset) {
+  int addIdOffset(int? offset) {
     fbBuilder.addOffset(0, offset);
     return fbBuilder.offset;
   }
-  int addVal(int val) {
+  int addVal(int? val) {
     fbBuilder.addInt64(1, val);
     return fbBuilder.offset;
   }
-  int addCount(int count) {
+  int addCount(int? count) {
     fbBuilder.addUint16(2, count);
     return fbBuilder.offset;
   }
@@ -898,14 +891,14 @@ class StatBuilder {
 }
 
 class StatObjectBuilder extends fb.ObjectBuilder {
-  final String _id;
-  final int _val;
-  final int _count;
+  final String? _id;
+  final int? _val;
+  final int? _count;
 
   StatObjectBuilder({
-    String id,
-    int val,
-    int count,
+    String? id,
+    int? val,
+    int? count,
   })
       : _id = id,
         _val = val,
@@ -913,15 +906,10 @@ class StatObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-    final int idOffset = fbBuilder.writeString(_id);
-
+  int finish(fb.Builder fbBuilder) {
+    final int? idOffset = fbBuilder.writeString(_id);
     fbBuilder.startTable();
-    if (idOffset != null) {
-      fbBuilder.addOffset(0, idOffset);
-    }
+    fbBuilder.addOffset(0, idOffset);
     fbBuilder.addInt64(1, _val);
     fbBuilder.addUint16(2, _count);
     return fbBuilder.endTable();
@@ -929,7 +917,7 @@ class StatObjectBuilder extends fb.ObjectBuilder {
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -957,7 +945,7 @@ class Referrable {
   ReferrableT unpack() => ReferrableT(
       id: id);
 
-  static int pack(fb.Builder fbBuilder, ReferrableT object) {
+  static int pack(fb.Builder fbBuilder, ReferrableT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -967,11 +955,9 @@ class ReferrableT {
   int id;
 
   ReferrableT({
-      this.id});
+      this.id = 0});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
     fbBuilder.startTable();
     fbBuilder.addUint64(0, id);
     return fbBuilder.endTable();
@@ -992,9 +978,7 @@ class _ReferrableReader extends fb.TableReader<Referrable> {
 }
 
 class ReferrableBuilder {
-  ReferrableBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  ReferrableBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -1002,7 +986,7 @@ class ReferrableBuilder {
     fbBuilder.startTable();
   }
 
-  int addId(int id) {
+  int addId(int? id) {
     fbBuilder.addUint64(0, id);
     return fbBuilder.offset;
   }
@@ -1013,19 +997,16 @@ class ReferrableBuilder {
 }
 
 class ReferrableObjectBuilder extends fb.ObjectBuilder {
-  final int _id;
+  final int? _id;
 
   ReferrableObjectBuilder({
-    int id,
+    int? id,
   })
       : _id = id;
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     fbBuilder.startTable();
     fbBuilder.addUint64(0, _id);
     return fbBuilder.endTable();
@@ -1033,7 +1014,7 @@ class ReferrableObjectBuilder extends fb.ObjectBuilder {
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -1052,29 +1033,29 @@ class Monster {
   final fb.BufferContext _bc;
   final int _bcOffset;
 
-  Vec3 get pos => Vec3.reader.vTableGet(_bc, _bcOffset, 4, null);
+  Vec3? get pos => Vec3.reader.vTableGetNullable(_bc, _bcOffset, 4);
   int get mana => const fb.Int16Reader().vTableGet(_bc, _bcOffset, 6, 150);
   int get hp => const fb.Int16Reader().vTableGet(_bc, _bcOffset, 8, 100);
-  String get name => const fb.StringReader().vTableGet(_bc, _bcOffset, 10, null);
-  List<int> get inventory => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGet(_bc, _bcOffset, 14, null);
-  Color get color => new Color.fromValue(const fb.Uint8Reader().vTableGet(_bc, _bcOffset, 16, 8));
-  AnyTypeId get testType => new AnyTypeId.fromValue(const fb.Uint8Reader().vTableGet(_bc, _bcOffset, 18, 0));
-  dynamic get test {
+  String? get name => const fb.StringReader().vTableGetNullable(_bc, _bcOffset, 10);
+  List<int>? get inventory => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGetNullable(_bc, _bcOffset, 14);
+  Color get color => Color.fromValue(const fb.Uint8Reader().vTableGet(_bc, _bcOffset, 16, 8));
+  AnyTypeId? get testType => AnyTypeId._createOrNull(const fb.Uint8Reader().vTableGetNullable(_bc, _bcOffset, 18));
+  dynamic? get test {
     switch (testType?.value) {
-      case 1: return Monster.reader.vTableGet(_bc, _bcOffset, 20, null);
-      case 2: return TestSimpleTableWithEnum.reader.vTableGet(_bc, _bcOffset, 20, null);
-      case 3: return my_game_example2.Monster.reader.vTableGet(_bc, _bcOffset, 20, null);
+      case 1: return Monster.reader.vTableGetNullable(_bc, _bcOffset, 20);
+      case 2: return TestSimpleTableWithEnum.reader.vTableGetNullable(_bc, _bcOffset, 20);
+      case 3: return my_game_example2.Monster.reader.vTableGetNullable(_bc, _bcOffset, 20);
       default: return null;
     }
   }
-  List<Test> get test4 => const fb.ListReader<Test>(Test.reader).vTableGet(_bc, _bcOffset, 22, null);
-  List<String> get testarrayofstring => const fb.ListReader<String>(const fb.StringReader()).vTableGet(_bc, _bcOffset, 24, null);
+  List<Test>? get test4 => const fb.ListReader<Test>(Test.reader).vTableGetNullable(_bc, _bcOffset, 22);
+  List<String>? get testarrayofstring => const fb.ListReader<String>(const fb.StringReader()).vTableGetNullable(_bc, _bcOffset, 24);
   ///  an example documentation comment: this will end up in the generated code
   ///  multiline too
-  List<Monster> get testarrayoftables => const fb.ListReader<Monster>(Monster.reader).vTableGet(_bc, _bcOffset, 26, null);
-  Monster get enemy => Monster.reader.vTableGet(_bc, _bcOffset, 28, null);
-  List<int> get testnestedflatbuffer => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGet(_bc, _bcOffset, 30, null);
-  Stat get testempty => Stat.reader.vTableGet(_bc, _bcOffset, 32, null);
+  List<Monster>? get testarrayoftables => const fb.ListReader<Monster>(Monster.reader).vTableGetNullable(_bc, _bcOffset, 26);
+  Monster? get enemy => Monster.reader.vTableGetNullable(_bc, _bcOffset, 28);
+  List<int>? get testnestedflatbuffer => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGetNullable(_bc, _bcOffset, 30);
+  Stat? get testempty => Stat.reader.vTableGetNullable(_bc, _bcOffset, 32);
   bool get testbool => const fb.BoolReader().vTableGet(_bc, _bcOffset, 34, false);
   int get testhashs32Fnv1 => const fb.Int32Reader().vTableGet(_bc, _bcOffset, 36, 0);
   int get testhashu32Fnv1 => const fb.Uint32Reader().vTableGet(_bc, _bcOffset, 38, 0);
@@ -1084,47 +1065,47 @@ class Monster {
   int get testhashu32Fnv1a => const fb.Uint32Reader().vTableGet(_bc, _bcOffset, 46, 0);
   int get testhashs64Fnv1a => const fb.Int64Reader().vTableGet(_bc, _bcOffset, 48, 0);
   int get testhashu64Fnv1a => const fb.Uint64Reader().vTableGet(_bc, _bcOffset, 50, 0);
-  List<bool> get testarrayofbools => const fb.ListReader<bool>(const fb.BoolReader()).vTableGet(_bc, _bcOffset, 52, null);
+  List<bool>? get testarrayofbools => const fb.ListReader<bool>(const fb.BoolReader()).vTableGetNullable(_bc, _bcOffset, 52);
   double get testf => const fb.Float32Reader().vTableGet(_bc, _bcOffset, 54, 3.14159);
   double get testf2 => const fb.Float32Reader().vTableGet(_bc, _bcOffset, 56, 3.0);
   double get testf3 => const fb.Float32Reader().vTableGet(_bc, _bcOffset, 58, 0.0);
-  List<String> get testarrayofstring2 => const fb.ListReader<String>(const fb.StringReader()).vTableGet(_bc, _bcOffset, 60, null);
-  List<Ability> get testarrayofsortedstruct => const fb.ListReader<Ability>(Ability.reader).vTableGet(_bc, _bcOffset, 62, null);
-  List<int> get flex => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGet(_bc, _bcOffset, 64, null);
-  List<Test> get test5 => const fb.ListReader<Test>(Test.reader).vTableGet(_bc, _bcOffset, 66, null);
-  List<int> get vectorOfLongs => const fb.ListReader<int>(const fb.Int64Reader()).vTableGet(_bc, _bcOffset, 68, null);
-  List<double> get vectorOfDoubles => const fb.ListReader<double>(const fb.Float64Reader()).vTableGet(_bc, _bcOffset, 70, null);
-  my_game.InParentNamespace get parentNamespaceTest => my_game.InParentNamespace.reader.vTableGet(_bc, _bcOffset, 72, null);
-  List<Referrable> get vectorOfReferrables => const fb.ListReader<Referrable>(Referrable.reader).vTableGet(_bc, _bcOffset, 74, null);
+  List<String>? get testarrayofstring2 => const fb.ListReader<String>(const fb.StringReader()).vTableGetNullable(_bc, _bcOffset, 60);
+  List<Ability>? get testarrayofsortedstruct => const fb.ListReader<Ability>(Ability.reader).vTableGetNullable(_bc, _bcOffset, 62);
+  List<int>? get flex => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGetNullable(_bc, _bcOffset, 64);
+  List<Test>? get test5 => const fb.ListReader<Test>(Test.reader).vTableGetNullable(_bc, _bcOffset, 66);
+  List<int>? get vectorOfLongs => const fb.ListReader<int>(const fb.Int64Reader()).vTableGetNullable(_bc, _bcOffset, 68);
+  List<double>? get vectorOfDoubles => const fb.ListReader<double>(const fb.Float64Reader()).vTableGetNullable(_bc, _bcOffset, 70);
+  my_game.InParentNamespace? get parentNamespaceTest => my_game.InParentNamespace.reader.vTableGetNullable(_bc, _bcOffset, 72);
+  List<Referrable>? get vectorOfReferrables => const fb.ListReader<Referrable>(Referrable.reader).vTableGetNullable(_bc, _bcOffset, 74);
   int get singleWeakReference => const fb.Uint64Reader().vTableGet(_bc, _bcOffset, 76, 0);
-  List<int> get vectorOfWeakReferences => const fb.ListReader<int>(const fb.Uint64Reader()).vTableGet(_bc, _bcOffset, 78, null);
-  List<Referrable> get vectorOfStrongReferrables => const fb.ListReader<Referrable>(Referrable.reader).vTableGet(_bc, _bcOffset, 80, null);
+  List<int>? get vectorOfWeakReferences => const fb.ListReader<int>(const fb.Uint64Reader()).vTableGetNullable(_bc, _bcOffset, 78);
+  List<Referrable>? get vectorOfStrongReferrables => const fb.ListReader<Referrable>(Referrable.reader).vTableGetNullable(_bc, _bcOffset, 80);
   int get coOwningReference => const fb.Uint64Reader().vTableGet(_bc, _bcOffset, 82, 0);
-  List<int> get vectorOfCoOwningReferences => const fb.ListReader<int>(const fb.Uint64Reader()).vTableGet(_bc, _bcOffset, 84, null);
+  List<int>? get vectorOfCoOwningReferences => const fb.ListReader<int>(const fb.Uint64Reader()).vTableGetNullable(_bc, _bcOffset, 84);
   int get nonOwningReference => const fb.Uint64Reader().vTableGet(_bc, _bcOffset, 86, 0);
-  List<int> get vectorOfNonOwningReferences => const fb.ListReader<int>(const fb.Uint64Reader()).vTableGet(_bc, _bcOffset, 88, null);
-  AnyUniqueAliasesTypeId get anyUniqueType => new AnyUniqueAliasesTypeId.fromValue(const fb.Uint8Reader().vTableGet(_bc, _bcOffset, 90, 0));
-  dynamic get anyUnique {
+  List<int>? get vectorOfNonOwningReferences => const fb.ListReader<int>(const fb.Uint64Reader()).vTableGetNullable(_bc, _bcOffset, 88);
+  AnyUniqueAliasesTypeId? get anyUniqueType => AnyUniqueAliasesTypeId._createOrNull(const fb.Uint8Reader().vTableGetNullable(_bc, _bcOffset, 90));
+  dynamic? get anyUnique {
     switch (anyUniqueType?.value) {
-      case 1: return Monster.reader.vTableGet(_bc, _bcOffset, 92, null);
-      case 2: return TestSimpleTableWithEnum.reader.vTableGet(_bc, _bcOffset, 92, null);
-      case 3: return my_game_example2.Monster.reader.vTableGet(_bc, _bcOffset, 92, null);
+      case 1: return Monster.reader.vTableGetNullable(_bc, _bcOffset, 92);
+      case 2: return TestSimpleTableWithEnum.reader.vTableGetNullable(_bc, _bcOffset, 92);
+      case 3: return my_game_example2.Monster.reader.vTableGetNullable(_bc, _bcOffset, 92);
       default: return null;
     }
   }
-  AnyAmbiguousAliasesTypeId get anyAmbiguousType => new AnyAmbiguousAliasesTypeId.fromValue(const fb.Uint8Reader().vTableGet(_bc, _bcOffset, 94, 0));
-  dynamic get anyAmbiguous {
+  AnyAmbiguousAliasesTypeId? get anyAmbiguousType => AnyAmbiguousAliasesTypeId._createOrNull(const fb.Uint8Reader().vTableGetNullable(_bc, _bcOffset, 94));
+  dynamic? get anyAmbiguous {
     switch (anyAmbiguousType?.value) {
-      case 1: return Monster.reader.vTableGet(_bc, _bcOffset, 96, null);
-      case 2: return Monster.reader.vTableGet(_bc, _bcOffset, 96, null);
-      case 3: return Monster.reader.vTableGet(_bc, _bcOffset, 96, null);
+      case 1: return Monster.reader.vTableGetNullable(_bc, _bcOffset, 96);
+      case 2: return Monster.reader.vTableGetNullable(_bc, _bcOffset, 96);
+      case 3: return Monster.reader.vTableGetNullable(_bc, _bcOffset, 96);
       default: return null;
     }
   }
-  List<Color> get vectorOfEnums => const fb.ListReader<Color>(Color.reader).vTableGet(_bc, _bcOffset, 98, null);
-  Race get signedEnum => new Race.fromValue(const fb.Int8Reader().vTableGet(_bc, _bcOffset, 100, -1));
-  List<int> get testrequirednestedflatbuffer => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGet(_bc, _bcOffset, 102, null);
-  List<Stat> get scalarKeySortedTables => const fb.ListReader<Stat>(Stat.reader).vTableGet(_bc, _bcOffset, 104, null);
+  List<Color>? get vectorOfEnums => const fb.ListReader<Color>(Color.reader).vTableGetNullable(_bc, _bcOffset, 98);
+  Race get signedEnum => Race.fromValue(const fb.Int8Reader().vTableGet(_bc, _bcOffset, 100, -1));
+  List<int>? get testrequirednestedflatbuffer => const fb.ListReader<int>(const fb.Uint8Reader()).vTableGetNullable(_bc, _bcOffset, 102);
+  List<Stat>? get scalarKeySortedTables => const fb.ListReader<Stat>(Stat.reader).vTableGetNullable(_bc, _bcOffset, 104);
 
   @override
   String toString() {
@@ -1140,9 +1121,9 @@ class Monster {
       color: color,
       testType: testType,
       test: test,
-      test4: test4?.map((e) => e.unpack())?.toList(),
+      test4: test4?.map((e) => e.unpack()).toList(),
       testarrayofstring: testarrayofstring,
-      testarrayoftables: testarrayoftables?.map((e) => e.unpack())?.toList(),
+      testarrayoftables: testarrayoftables?.map((e) => e.unpack()).toList(),
       enemy: enemy?.unpack(),
       testnestedflatbuffer: testnestedflatbuffer,
       testempty: testempty?.unpack(),
@@ -1160,16 +1141,16 @@ class Monster {
       testf2: testf2,
       testf3: testf3,
       testarrayofstring2: testarrayofstring2,
-      testarrayofsortedstruct: testarrayofsortedstruct?.map((e) => e.unpack())?.toList(),
+      testarrayofsortedstruct: testarrayofsortedstruct?.map((e) => e.unpack()).toList(),
       flex: flex,
-      test5: test5?.map((e) => e.unpack())?.toList(),
+      test5: test5?.map((e) => e.unpack()).toList(),
       vectorOfLongs: vectorOfLongs,
       vectorOfDoubles: vectorOfDoubles,
       parentNamespaceTest: parentNamespaceTest?.unpack(),
-      vectorOfReferrables: vectorOfReferrables?.map((e) => e.unpack())?.toList(),
+      vectorOfReferrables: vectorOfReferrables?.map((e) => e.unpack()).toList(),
       singleWeakReference: singleWeakReference,
       vectorOfWeakReferences: vectorOfWeakReferences,
-      vectorOfStrongReferrables: vectorOfStrongReferrables?.map((e) => e.unpack())?.toList(),
+      vectorOfStrongReferrables: vectorOfStrongReferrables?.map((e) => e.unpack()).toList(),
       coOwningReference: coOwningReference,
       vectorOfCoOwningReferences: vectorOfCoOwningReferences,
       nonOwningReference: nonOwningReference,
@@ -1181,9 +1162,9 @@ class Monster {
       vectorOfEnums: vectorOfEnums,
       signedEnum: signedEnum,
       testrequirednestedflatbuffer: testrequirednestedflatbuffer,
-      scalarKeySortedTables: scalarKeySortedTables?.map((e) => e.unpack())?.toList());
+      scalarKeySortedTables: scalarKeySortedTables?.map((e) => e.unpack()).toList());
 
-  static int pack(fb.Builder fbBuilder, MonsterT object) {
+  static int pack(fb.Builder fbBuilder, MonsterT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -1191,22 +1172,22 @@ class Monster {
 
 ///  an example documentation comment: "monster object"
 class MonsterT {
-  Vec3T pos;
+  Vec3T? pos;
   int mana;
   int hp;
-  String name;
-  List<int> inventory;
+  String? name;
+  List<int>? inventory;
   Color color;
-  AnyTypeId testType;
-  dynamic test;
-  List<TestT> test4;
-  List<String> testarrayofstring;
+  AnyTypeId? testType;
+  dynamic? test;
+  List<TestT>? test4;
+  List<String>? testarrayofstring;
   ///  an example documentation comment: this will end up in the generated code
   ///  multiline too
-  List<MonsterT> testarrayoftables;
-  MonsterT enemy;
-  List<int> testnestedflatbuffer;
-  StatT testempty;
+  List<MonsterT>? testarrayoftables;
+  MonsterT? enemy;
+  List<int>? testnestedflatbuffer;
+  StatT? testempty;
   bool testbool;
   int testhashs32Fnv1;
   int testhashu32Fnv1;
@@ -1216,41 +1197,41 @@ class MonsterT {
   int testhashu32Fnv1a;
   int testhashs64Fnv1a;
   int testhashu64Fnv1a;
-  List<bool> testarrayofbools;
+  List<bool>? testarrayofbools;
   double testf;
   double testf2;
   double testf3;
-  List<String> testarrayofstring2;
-  List<AbilityT> testarrayofsortedstruct;
-  List<int> flex;
-  List<TestT> test5;
-  List<int> vectorOfLongs;
-  List<double> vectorOfDoubles;
-  my_game.InParentNamespaceT parentNamespaceTest;
-  List<ReferrableT> vectorOfReferrables;
+  List<String>? testarrayofstring2;
+  List<AbilityT>? testarrayofsortedstruct;
+  List<int>? flex;
+  List<TestT>? test5;
+  List<int>? vectorOfLongs;
+  List<double>? vectorOfDoubles;
+  my_game.InParentNamespaceT? parentNamespaceTest;
+  List<ReferrableT>? vectorOfReferrables;
   int singleWeakReference;
-  List<int> vectorOfWeakReferences;
-  List<ReferrableT> vectorOfStrongReferrables;
+  List<int>? vectorOfWeakReferences;
+  List<ReferrableT>? vectorOfStrongReferrables;
   int coOwningReference;
-  List<int> vectorOfCoOwningReferences;
+  List<int>? vectorOfCoOwningReferences;
   int nonOwningReference;
-  List<int> vectorOfNonOwningReferences;
-  AnyUniqueAliasesTypeId anyUniqueType;
-  dynamic anyUnique;
-  AnyAmbiguousAliasesTypeId anyAmbiguousType;
-  dynamic anyAmbiguous;
-  List<Color> vectorOfEnums;
+  List<int>? vectorOfNonOwningReferences;
+  AnyUniqueAliasesTypeId? anyUniqueType;
+  dynamic? anyUnique;
+  AnyAmbiguousAliasesTypeId? anyAmbiguousType;
+  dynamic? anyAmbiguous;
+  List<Color>? vectorOfEnums;
   Race signedEnum;
-  List<int> testrequirednestedflatbuffer;
-  List<StatT> scalarKeySortedTables;
+  List<int>? testrequirednestedflatbuffer;
+  List<StatT>? scalarKeySortedTables;
 
   MonsterT({
       this.pos,
-      this.mana,
-      this.hp,
+      this.mana = 150,
+      this.hp = 100,
       this.name,
       this.inventory,
-      this.color,
+      this.color = Color.Blue,
       this.testType,
       this.test,
       this.test4,
@@ -1259,19 +1240,19 @@ class MonsterT {
       this.enemy,
       this.testnestedflatbuffer,
       this.testempty,
-      this.testbool,
-      this.testhashs32Fnv1,
-      this.testhashu32Fnv1,
-      this.testhashs64Fnv1,
-      this.testhashu64Fnv1,
-      this.testhashs32Fnv1a,
-      this.testhashu32Fnv1a,
-      this.testhashs64Fnv1a,
-      this.testhashu64Fnv1a,
+      this.testbool = false,
+      this.testhashs32Fnv1 = 0,
+      this.testhashu32Fnv1 = 0,
+      this.testhashs64Fnv1 = 0,
+      this.testhashu64Fnv1 = 0,
+      this.testhashs32Fnv1a = 0,
+      this.testhashu32Fnv1a = 0,
+      this.testhashs64Fnv1a = 0,
+      this.testhashu64Fnv1a = 0,
       this.testarrayofbools,
-      this.testf,
-      this.testf2,
-      this.testf3,
+      this.testf = 3.14159,
+      this.testf2 = 3.0,
+      this.testf3 = 0.0,
       this.testarrayofstring2,
       this.testarrayofsortedstruct,
       this.flex,
@@ -1280,133 +1261,113 @@ class MonsterT {
       this.vectorOfDoubles,
       this.parentNamespaceTest,
       this.vectorOfReferrables,
-      this.singleWeakReference,
+      this.singleWeakReference = 0,
       this.vectorOfWeakReferences,
       this.vectorOfStrongReferrables,
-      this.coOwningReference,
+      this.coOwningReference = 0,
       this.vectorOfCoOwningReferences,
-      this.nonOwningReference,
+      this.nonOwningReference = 0,
       this.vectorOfNonOwningReferences,
       this.anyUniqueType,
       this.anyUnique,
       this.anyAmbiguousType,
       this.anyAmbiguous,
       this.vectorOfEnums,
-      this.signedEnum,
+      this.signedEnum = Race.None,
       this.testrequirednestedflatbuffer,
       this.scalarKeySortedTables});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-    final int nameOffset = fbBuilder.writeString(name);
-    final int inventoryOffset = inventory?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(inventory)
+    final int? nameOffset = fbBuilder.writeString(name);
+    final int? inventoryOffset = inventory?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(inventory!)
         : null;
-    final int testOffset = test?.pack(fbBuilder);
-    int test4Offset = null;
+    final int? testOffset = test?.pack(fbBuilder);
+    int? test4Offset = null;
     if (test4?.isNotEmpty == true) {
-      test4.forEach((e) => e.pack(fbBuilder));
-      test4Offset = fbBuilder.endStructVector(test4.length);
+      test4!.forEach((e) => e.pack(fbBuilder));
+      test4Offset = fbBuilder.endStructVector(test4!.length);
     }
-    final int testarrayofstringOffset = testarrayofstring?.isNotEmpty == true
-        ? fbBuilder.writeList(testarrayofstring.map((b) => fbBuilder.writeString(b)).toList())
+    final int? testarrayofstringOffset = testarrayofstring?.isNotEmpty == true
+        ? fbBuilder.writeList(testarrayofstring!.map((b) => fbBuilder.writeString(b)!).toList())
         : null;
-    final int testarrayoftablesOffset = testarrayoftables?.isNotEmpty == true
-        ? fbBuilder.writeList(testarrayoftables.map((b) => b.pack(fbBuilder)).toList())
+    final int? testarrayoftablesOffset = testarrayoftables?.isNotEmpty == true
+        ? fbBuilder.writeList(testarrayoftables!.map((b) => b.pack(fbBuilder)).toList())
         : null;
-    final int enemyOffset = enemy?.pack(fbBuilder);
-    final int testnestedflatbufferOffset = testnestedflatbuffer?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(testnestedflatbuffer)
+    final int? enemyOffset = enemy?.pack(fbBuilder);
+    final int? testnestedflatbufferOffset = testnestedflatbuffer?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(testnestedflatbuffer!)
         : null;
-    final int testemptyOffset = testempty?.pack(fbBuilder);
-    final int testarrayofboolsOffset = testarrayofbools?.isNotEmpty == true
-        ? fbBuilder.writeListBool(testarrayofbools)
+    final int? testemptyOffset = testempty?.pack(fbBuilder);
+    final int? testarrayofboolsOffset = testarrayofbools?.isNotEmpty == true
+        ? fbBuilder.writeListBool(testarrayofbools!)
         : null;
-    final int testarrayofstring2Offset = testarrayofstring2?.isNotEmpty == true
-        ? fbBuilder.writeList(testarrayofstring2.map((b) => fbBuilder.writeString(b)).toList())
+    final int? testarrayofstring2Offset = testarrayofstring2?.isNotEmpty == true
+        ? fbBuilder.writeList(testarrayofstring2!.map((b) => fbBuilder.writeString(b)!).toList())
         : null;
-    int testarrayofsortedstructOffset = null;
+    int? testarrayofsortedstructOffset = null;
     if (testarrayofsortedstruct?.isNotEmpty == true) {
-      testarrayofsortedstruct.forEach((e) => e.pack(fbBuilder));
-      testarrayofsortedstructOffset = fbBuilder.endStructVector(testarrayofsortedstruct.length);
+      testarrayofsortedstruct!.forEach((e) => e.pack(fbBuilder));
+      testarrayofsortedstructOffset = fbBuilder.endStructVector(testarrayofsortedstruct!.length);
     }
-    final int flexOffset = flex?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(flex)
+    final int? flexOffset = flex?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(flex!)
         : null;
-    int test5Offset = null;
+    int? test5Offset = null;
     if (test5?.isNotEmpty == true) {
-      test5.forEach((e) => e.pack(fbBuilder));
-      test5Offset = fbBuilder.endStructVector(test5.length);
+      test5!.forEach((e) => e.pack(fbBuilder));
+      test5Offset = fbBuilder.endStructVector(test5!.length);
     }
-    final int vectorOfLongsOffset = vectorOfLongs?.isNotEmpty == true
-        ? fbBuilder.writeListInt64(vectorOfLongs)
+    final int? vectorOfLongsOffset = vectorOfLongs?.isNotEmpty == true
+        ? fbBuilder.writeListInt64(vectorOfLongs!)
         : null;
-    final int vectorOfDoublesOffset = vectorOfDoubles?.isNotEmpty == true
-        ? fbBuilder.writeListFloat64(vectorOfDoubles)
+    final int? vectorOfDoublesOffset = vectorOfDoubles?.isNotEmpty == true
+        ? fbBuilder.writeListFloat64(vectorOfDoubles!)
         : null;
-    final int parentNamespaceTestOffset = parentNamespaceTest?.pack(fbBuilder);
-    final int vectorOfReferrablesOffset = vectorOfReferrables?.isNotEmpty == true
-        ? fbBuilder.writeList(vectorOfReferrables.map((b) => b.pack(fbBuilder)).toList())
+    final int? parentNamespaceTestOffset = parentNamespaceTest?.pack(fbBuilder);
+    final int? vectorOfReferrablesOffset = vectorOfReferrables?.isNotEmpty == true
+        ? fbBuilder.writeList(vectorOfReferrables!.map((b) => b.pack(fbBuilder)).toList())
         : null;
-    final int vectorOfWeakReferencesOffset = vectorOfWeakReferences?.isNotEmpty == true
-        ? fbBuilder.writeListUint64(vectorOfWeakReferences)
+    final int? vectorOfWeakReferencesOffset = vectorOfWeakReferences?.isNotEmpty == true
+        ? fbBuilder.writeListUint64(vectorOfWeakReferences!)
         : null;
-    final int vectorOfStrongReferrablesOffset = vectorOfStrongReferrables?.isNotEmpty == true
-        ? fbBuilder.writeList(vectorOfStrongReferrables.map((b) => b.pack(fbBuilder)).toList())
+    final int? vectorOfStrongReferrablesOffset = vectorOfStrongReferrables?.isNotEmpty == true
+        ? fbBuilder.writeList(vectorOfStrongReferrables!.map((b) => b.pack(fbBuilder)).toList())
         : null;
-    final int vectorOfCoOwningReferencesOffset = vectorOfCoOwningReferences?.isNotEmpty == true
-        ? fbBuilder.writeListUint64(vectorOfCoOwningReferences)
+    final int? vectorOfCoOwningReferencesOffset = vectorOfCoOwningReferences?.isNotEmpty == true
+        ? fbBuilder.writeListUint64(vectorOfCoOwningReferences!)
         : null;
-    final int vectorOfNonOwningReferencesOffset = vectorOfNonOwningReferences?.isNotEmpty == true
-        ? fbBuilder.writeListUint64(vectorOfNonOwningReferences)
+    final int? vectorOfNonOwningReferencesOffset = vectorOfNonOwningReferences?.isNotEmpty == true
+        ? fbBuilder.writeListUint64(vectorOfNonOwningReferences!)
         : null;
-    final int anyUniqueOffset = anyUnique?.pack(fbBuilder);
-    final int anyAmbiguousOffset = anyAmbiguous?.pack(fbBuilder);
-    final int vectorOfEnumsOffset = vectorOfEnums?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(vectorOfEnums.map((f) => f.value).toList())
+    final int? anyUniqueOffset = anyUnique?.pack(fbBuilder);
+    final int? anyAmbiguousOffset = anyAmbiguous?.pack(fbBuilder);
+    final int? vectorOfEnumsOffset = vectorOfEnums?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(vectorOfEnums!.map((f) => f.value).toList())
         : null;
-    final int testrequirednestedflatbufferOffset = testrequirednestedflatbuffer?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(testrequirednestedflatbuffer)
+    final int? testrequirednestedflatbufferOffset = testrequirednestedflatbuffer?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(testrequirednestedflatbuffer!)
         : null;
-    final int scalarKeySortedTablesOffset = scalarKeySortedTables?.isNotEmpty == true
-        ? fbBuilder.writeList(scalarKeySortedTables.map((b) => b.pack(fbBuilder)).toList())
+    final int? scalarKeySortedTablesOffset = scalarKeySortedTables?.isNotEmpty == true
+        ? fbBuilder.writeList(scalarKeySortedTables!.map((b) => b.pack(fbBuilder)).toList())
         : null;
-
     fbBuilder.startTable();
     if (pos != null) {
-      fbBuilder.addStruct(0, pos.pack(fbBuilder));
+      fbBuilder.addStruct(0, pos!.pack(fbBuilder));
     }
     fbBuilder.addInt16(1, mana);
     fbBuilder.addInt16(2, hp);
-    if (nameOffset != null) {
-      fbBuilder.addOffset(3, nameOffset);
-    }
-    if (inventoryOffset != null) {
-      fbBuilder.addOffset(5, inventoryOffset);
-    }
-    fbBuilder.addUint8(6, color?.value);
+    fbBuilder.addOffset(3, nameOffset);
+    fbBuilder.addOffset(5, inventoryOffset);
+    fbBuilder.addUint8(6, color.value);
     fbBuilder.addUint8(7, testType?.value);
-    if (testOffset != null) {
-      fbBuilder.addOffset(8, testOffset);
-    }
-    if (test4Offset != null) {
-      fbBuilder.addOffset(9, test4Offset);
-    }
-    if (testarrayofstringOffset != null) {
-      fbBuilder.addOffset(10, testarrayofstringOffset);
-    }
-    if (testarrayoftablesOffset != null) {
-      fbBuilder.addOffset(11, testarrayoftablesOffset);
-    }
-    if (enemyOffset != null) {
-      fbBuilder.addOffset(12, enemyOffset);
-    }
-    if (testnestedflatbufferOffset != null) {
-      fbBuilder.addOffset(13, testnestedflatbufferOffset);
-    }
-    if (testemptyOffset != null) {
-      fbBuilder.addOffset(14, testemptyOffset);
-    }
+    fbBuilder.addOffset(8, testOffset);
+    fbBuilder.addOffset(9, test4Offset);
+    fbBuilder.addOffset(10, testarrayofstringOffset);
+    fbBuilder.addOffset(11, testarrayoftablesOffset);
+    fbBuilder.addOffset(12, enemyOffset);
+    fbBuilder.addOffset(13, testnestedflatbufferOffset);
+    fbBuilder.addOffset(14, testemptyOffset);
     fbBuilder.addBool(15, testbool);
     fbBuilder.addInt32(16, testhashs32Fnv1);
     fbBuilder.addUint32(17, testhashu32Fnv1);
@@ -1416,69 +1377,33 @@ class MonsterT {
     fbBuilder.addUint32(21, testhashu32Fnv1a);
     fbBuilder.addInt64(22, testhashs64Fnv1a);
     fbBuilder.addUint64(23, testhashu64Fnv1a);
-    if (testarrayofboolsOffset != null) {
-      fbBuilder.addOffset(24, testarrayofboolsOffset);
-    }
+    fbBuilder.addOffset(24, testarrayofboolsOffset);
     fbBuilder.addFloat32(25, testf);
     fbBuilder.addFloat32(26, testf2);
     fbBuilder.addFloat32(27, testf3);
-    if (testarrayofstring2Offset != null) {
-      fbBuilder.addOffset(28, testarrayofstring2Offset);
-    }
-    if (testarrayofsortedstructOffset != null) {
-      fbBuilder.addOffset(29, testarrayofsortedstructOffset);
-    }
-    if (flexOffset != null) {
-      fbBuilder.addOffset(30, flexOffset);
-    }
-    if (test5Offset != null) {
-      fbBuilder.addOffset(31, test5Offset);
-    }
-    if (vectorOfLongsOffset != null) {
-      fbBuilder.addOffset(32, vectorOfLongsOffset);
-    }
-    if (vectorOfDoublesOffset != null) {
-      fbBuilder.addOffset(33, vectorOfDoublesOffset);
-    }
-    if (parentNamespaceTestOffset != null) {
-      fbBuilder.addOffset(34, parentNamespaceTestOffset);
-    }
-    if (vectorOfReferrablesOffset != null) {
-      fbBuilder.addOffset(35, vectorOfReferrablesOffset);
-    }
+    fbBuilder.addOffset(28, testarrayofstring2Offset);
+    fbBuilder.addOffset(29, testarrayofsortedstructOffset);
+    fbBuilder.addOffset(30, flexOffset);
+    fbBuilder.addOffset(31, test5Offset);
+    fbBuilder.addOffset(32, vectorOfLongsOffset);
+    fbBuilder.addOffset(33, vectorOfDoublesOffset);
+    fbBuilder.addOffset(34, parentNamespaceTestOffset);
+    fbBuilder.addOffset(35, vectorOfReferrablesOffset);
     fbBuilder.addUint64(36, singleWeakReference);
-    if (vectorOfWeakReferencesOffset != null) {
-      fbBuilder.addOffset(37, vectorOfWeakReferencesOffset);
-    }
-    if (vectorOfStrongReferrablesOffset != null) {
-      fbBuilder.addOffset(38, vectorOfStrongReferrablesOffset);
-    }
+    fbBuilder.addOffset(37, vectorOfWeakReferencesOffset);
+    fbBuilder.addOffset(38, vectorOfStrongReferrablesOffset);
     fbBuilder.addUint64(39, coOwningReference);
-    if (vectorOfCoOwningReferencesOffset != null) {
-      fbBuilder.addOffset(40, vectorOfCoOwningReferencesOffset);
-    }
+    fbBuilder.addOffset(40, vectorOfCoOwningReferencesOffset);
     fbBuilder.addUint64(41, nonOwningReference);
-    if (vectorOfNonOwningReferencesOffset != null) {
-      fbBuilder.addOffset(42, vectorOfNonOwningReferencesOffset);
-    }
+    fbBuilder.addOffset(42, vectorOfNonOwningReferencesOffset);
     fbBuilder.addUint8(43, anyUniqueType?.value);
-    if (anyUniqueOffset != null) {
-      fbBuilder.addOffset(44, anyUniqueOffset);
-    }
+    fbBuilder.addOffset(44, anyUniqueOffset);
     fbBuilder.addUint8(45, anyAmbiguousType?.value);
-    if (anyAmbiguousOffset != null) {
-      fbBuilder.addOffset(46, anyAmbiguousOffset);
-    }
-    if (vectorOfEnumsOffset != null) {
-      fbBuilder.addOffset(47, vectorOfEnumsOffset);
-    }
-    fbBuilder.addInt8(48, signedEnum?.value);
-    if (testrequirednestedflatbufferOffset != null) {
-      fbBuilder.addOffset(49, testrequirednestedflatbufferOffset);
-    }
-    if (scalarKeySortedTablesOffset != null) {
-      fbBuilder.addOffset(50, scalarKeySortedTablesOffset);
-    }
+    fbBuilder.addOffset(46, anyAmbiguousOffset);
+    fbBuilder.addOffset(47, vectorOfEnumsOffset);
+    fbBuilder.addInt8(48, signedEnum.value);
+    fbBuilder.addOffset(49, testrequirednestedflatbufferOffset);
+    fbBuilder.addOffset(50, scalarKeySortedTablesOffset);
     return fbBuilder.endTable();
   }
 
@@ -1497,9 +1422,7 @@ class _MonsterReader extends fb.TableReader<Monster> {
 }
 
 class MonsterBuilder {
-  MonsterBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  MonsterBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -1511,199 +1434,199 @@ class MonsterBuilder {
     fbBuilder.addStruct(0, offset);
     return fbBuilder.offset;
   }
-  int addMana(int mana) {
+  int addMana(int? mana) {
     fbBuilder.addInt16(1, mana);
     return fbBuilder.offset;
   }
-  int addHp(int hp) {
+  int addHp(int? hp) {
     fbBuilder.addInt16(2, hp);
     return fbBuilder.offset;
   }
-  int addNameOffset(int offset) {
+  int addNameOffset(int? offset) {
     fbBuilder.addOffset(3, offset);
     return fbBuilder.offset;
   }
-  int addInventoryOffset(int offset) {
+  int addInventoryOffset(int? offset) {
     fbBuilder.addOffset(5, offset);
     return fbBuilder.offset;
   }
-  int addColor(Color color) {
+  int addColor(Color? color) {
     fbBuilder.addUint8(6, color?.value);
     return fbBuilder.offset;
   }
-  int addTestType(AnyTypeId testType) {
+  int addTestType(AnyTypeId? testType) {
     fbBuilder.addUint8(7, testType?.value);
     return fbBuilder.offset;
   }
-  int addTestOffset(int offset) {
+  int addTestOffset(int? offset) {
     fbBuilder.addOffset(8, offset);
     return fbBuilder.offset;
   }
-  int addTest4Offset(int offset) {
+  int addTest4Offset(int? offset) {
     fbBuilder.addOffset(9, offset);
     return fbBuilder.offset;
   }
-  int addTestarrayofstringOffset(int offset) {
+  int addTestarrayofstringOffset(int? offset) {
     fbBuilder.addOffset(10, offset);
     return fbBuilder.offset;
   }
-  int addTestarrayoftablesOffset(int offset) {
+  int addTestarrayoftablesOffset(int? offset) {
     fbBuilder.addOffset(11, offset);
     return fbBuilder.offset;
   }
-  int addEnemyOffset(int offset) {
+  int addEnemyOffset(int? offset) {
     fbBuilder.addOffset(12, offset);
     return fbBuilder.offset;
   }
-  int addTestnestedflatbufferOffset(int offset) {
+  int addTestnestedflatbufferOffset(int? offset) {
     fbBuilder.addOffset(13, offset);
     return fbBuilder.offset;
   }
-  int addTestemptyOffset(int offset) {
+  int addTestemptyOffset(int? offset) {
     fbBuilder.addOffset(14, offset);
     return fbBuilder.offset;
   }
-  int addTestbool(bool testbool) {
+  int addTestbool(bool? testbool) {
     fbBuilder.addBool(15, testbool);
     return fbBuilder.offset;
   }
-  int addTesthashs32Fnv1(int testhashs32Fnv1) {
+  int addTesthashs32Fnv1(int? testhashs32Fnv1) {
     fbBuilder.addInt32(16, testhashs32Fnv1);
     return fbBuilder.offset;
   }
-  int addTesthashu32Fnv1(int testhashu32Fnv1) {
+  int addTesthashu32Fnv1(int? testhashu32Fnv1) {
     fbBuilder.addUint32(17, testhashu32Fnv1);
     return fbBuilder.offset;
   }
-  int addTesthashs64Fnv1(int testhashs64Fnv1) {
+  int addTesthashs64Fnv1(int? testhashs64Fnv1) {
     fbBuilder.addInt64(18, testhashs64Fnv1);
     return fbBuilder.offset;
   }
-  int addTesthashu64Fnv1(int testhashu64Fnv1) {
+  int addTesthashu64Fnv1(int? testhashu64Fnv1) {
     fbBuilder.addUint64(19, testhashu64Fnv1);
     return fbBuilder.offset;
   }
-  int addTesthashs32Fnv1a(int testhashs32Fnv1a) {
+  int addTesthashs32Fnv1a(int? testhashs32Fnv1a) {
     fbBuilder.addInt32(20, testhashs32Fnv1a);
     return fbBuilder.offset;
   }
-  int addTesthashu32Fnv1a(int testhashu32Fnv1a) {
+  int addTesthashu32Fnv1a(int? testhashu32Fnv1a) {
     fbBuilder.addUint32(21, testhashu32Fnv1a);
     return fbBuilder.offset;
   }
-  int addTesthashs64Fnv1a(int testhashs64Fnv1a) {
+  int addTesthashs64Fnv1a(int? testhashs64Fnv1a) {
     fbBuilder.addInt64(22, testhashs64Fnv1a);
     return fbBuilder.offset;
   }
-  int addTesthashu64Fnv1a(int testhashu64Fnv1a) {
+  int addTesthashu64Fnv1a(int? testhashu64Fnv1a) {
     fbBuilder.addUint64(23, testhashu64Fnv1a);
     return fbBuilder.offset;
   }
-  int addTestarrayofboolsOffset(int offset) {
+  int addTestarrayofboolsOffset(int? offset) {
     fbBuilder.addOffset(24, offset);
     return fbBuilder.offset;
   }
-  int addTestf(double testf) {
+  int addTestf(double? testf) {
     fbBuilder.addFloat32(25, testf);
     return fbBuilder.offset;
   }
-  int addTestf2(double testf2) {
+  int addTestf2(double? testf2) {
     fbBuilder.addFloat32(26, testf2);
     return fbBuilder.offset;
   }
-  int addTestf3(double testf3) {
+  int addTestf3(double? testf3) {
     fbBuilder.addFloat32(27, testf3);
     return fbBuilder.offset;
   }
-  int addTestarrayofstring2Offset(int offset) {
+  int addTestarrayofstring2Offset(int? offset) {
     fbBuilder.addOffset(28, offset);
     return fbBuilder.offset;
   }
-  int addTestarrayofsortedstructOffset(int offset) {
+  int addTestarrayofsortedstructOffset(int? offset) {
     fbBuilder.addOffset(29, offset);
     return fbBuilder.offset;
   }
-  int addFlexOffset(int offset) {
+  int addFlexOffset(int? offset) {
     fbBuilder.addOffset(30, offset);
     return fbBuilder.offset;
   }
-  int addTest5Offset(int offset) {
+  int addTest5Offset(int? offset) {
     fbBuilder.addOffset(31, offset);
     return fbBuilder.offset;
   }
-  int addVectorOfLongsOffset(int offset) {
+  int addVectorOfLongsOffset(int? offset) {
     fbBuilder.addOffset(32, offset);
     return fbBuilder.offset;
   }
-  int addVectorOfDoublesOffset(int offset) {
+  int addVectorOfDoublesOffset(int? offset) {
     fbBuilder.addOffset(33, offset);
     return fbBuilder.offset;
   }
-  int addParentNamespaceTestOffset(int offset) {
+  int addParentNamespaceTestOffset(int? offset) {
     fbBuilder.addOffset(34, offset);
     return fbBuilder.offset;
   }
-  int addVectorOfReferrablesOffset(int offset) {
+  int addVectorOfReferrablesOffset(int? offset) {
     fbBuilder.addOffset(35, offset);
     return fbBuilder.offset;
   }
-  int addSingleWeakReference(int singleWeakReference) {
+  int addSingleWeakReference(int? singleWeakReference) {
     fbBuilder.addUint64(36, singleWeakReference);
     return fbBuilder.offset;
   }
-  int addVectorOfWeakReferencesOffset(int offset) {
+  int addVectorOfWeakReferencesOffset(int? offset) {
     fbBuilder.addOffset(37, offset);
     return fbBuilder.offset;
   }
-  int addVectorOfStrongReferrablesOffset(int offset) {
+  int addVectorOfStrongReferrablesOffset(int? offset) {
     fbBuilder.addOffset(38, offset);
     return fbBuilder.offset;
   }
-  int addCoOwningReference(int coOwningReference) {
+  int addCoOwningReference(int? coOwningReference) {
     fbBuilder.addUint64(39, coOwningReference);
     return fbBuilder.offset;
   }
-  int addVectorOfCoOwningReferencesOffset(int offset) {
+  int addVectorOfCoOwningReferencesOffset(int? offset) {
     fbBuilder.addOffset(40, offset);
     return fbBuilder.offset;
   }
-  int addNonOwningReference(int nonOwningReference) {
+  int addNonOwningReference(int? nonOwningReference) {
     fbBuilder.addUint64(41, nonOwningReference);
     return fbBuilder.offset;
   }
-  int addVectorOfNonOwningReferencesOffset(int offset) {
+  int addVectorOfNonOwningReferencesOffset(int? offset) {
     fbBuilder.addOffset(42, offset);
     return fbBuilder.offset;
   }
-  int addAnyUniqueType(AnyUniqueAliasesTypeId anyUniqueType) {
+  int addAnyUniqueType(AnyUniqueAliasesTypeId? anyUniqueType) {
     fbBuilder.addUint8(43, anyUniqueType?.value);
     return fbBuilder.offset;
   }
-  int addAnyUniqueOffset(int offset) {
+  int addAnyUniqueOffset(int? offset) {
     fbBuilder.addOffset(44, offset);
     return fbBuilder.offset;
   }
-  int addAnyAmbiguousType(AnyAmbiguousAliasesTypeId anyAmbiguousType) {
+  int addAnyAmbiguousType(AnyAmbiguousAliasesTypeId? anyAmbiguousType) {
     fbBuilder.addUint8(45, anyAmbiguousType?.value);
     return fbBuilder.offset;
   }
-  int addAnyAmbiguousOffset(int offset) {
+  int addAnyAmbiguousOffset(int? offset) {
     fbBuilder.addOffset(46, offset);
     return fbBuilder.offset;
   }
-  int addVectorOfEnumsOffset(int offset) {
+  int addVectorOfEnumsOffset(int? offset) {
     fbBuilder.addOffset(47, offset);
     return fbBuilder.offset;
   }
-  int addSignedEnum(Race signedEnum) {
+  int addSignedEnum(Race? signedEnum) {
     fbBuilder.addInt8(48, signedEnum?.value);
     return fbBuilder.offset;
   }
-  int addTestrequirednestedflatbufferOffset(int offset) {
+  int addTestrequirednestedflatbufferOffset(int? offset) {
     fbBuilder.addOffset(49, offset);
     return fbBuilder.offset;
   }
-  int addScalarKeySortedTablesOffset(int offset) {
+  int addScalarKeySortedTablesOffset(int? offset) {
     fbBuilder.addOffset(50, offset);
     return fbBuilder.offset;
   }
@@ -1714,108 +1637,108 @@ class MonsterBuilder {
 }
 
 class MonsterObjectBuilder extends fb.ObjectBuilder {
-  final Vec3ObjectBuilder _pos;
-  final int _mana;
-  final int _hp;
-  final String _name;
-  final List<int> _inventory;
-  final Color _color;
-  final AnyTypeId _testType;
-  final dynamic _test;
-  final List<TestObjectBuilder> _test4;
-  final List<String> _testarrayofstring;
-  final List<MonsterObjectBuilder> _testarrayoftables;
-  final MonsterObjectBuilder _enemy;
-  final List<int> _testnestedflatbuffer;
-  final StatObjectBuilder _testempty;
-  final bool _testbool;
-  final int _testhashs32Fnv1;
-  final int _testhashu32Fnv1;
-  final int _testhashs64Fnv1;
-  final int _testhashu64Fnv1;
-  final int _testhashs32Fnv1a;
-  final int _testhashu32Fnv1a;
-  final int _testhashs64Fnv1a;
-  final int _testhashu64Fnv1a;
-  final List<bool> _testarrayofbools;
-  final double _testf;
-  final double _testf2;
-  final double _testf3;
-  final List<String> _testarrayofstring2;
-  final List<AbilityObjectBuilder> _testarrayofsortedstruct;
-  final List<int> _flex;
-  final List<TestObjectBuilder> _test5;
-  final List<int> _vectorOfLongs;
-  final List<double> _vectorOfDoubles;
-  final my_game.InParentNamespaceObjectBuilder _parentNamespaceTest;
-  final List<ReferrableObjectBuilder> _vectorOfReferrables;
-  final int _singleWeakReference;
-  final List<int> _vectorOfWeakReferences;
-  final List<ReferrableObjectBuilder> _vectorOfStrongReferrables;
-  final int _coOwningReference;
-  final List<int> _vectorOfCoOwningReferences;
-  final int _nonOwningReference;
-  final List<int> _vectorOfNonOwningReferences;
-  final AnyUniqueAliasesTypeId _anyUniqueType;
-  final dynamic _anyUnique;
-  final AnyAmbiguousAliasesTypeId _anyAmbiguousType;
-  final dynamic _anyAmbiguous;
-  final List<Color> _vectorOfEnums;
-  final Race _signedEnum;
-  final List<int> _testrequirednestedflatbuffer;
-  final List<StatObjectBuilder> _scalarKeySortedTables;
+  final Vec3ObjectBuilder? _pos;
+  final int? _mana;
+  final int? _hp;
+  final String? _name;
+  final List<int>? _inventory;
+  final Color? _color;
+  final AnyTypeId? _testType;
+  final dynamic? _test;
+  final List<TestObjectBuilder>? _test4;
+  final List<String>? _testarrayofstring;
+  final List<MonsterObjectBuilder>? _testarrayoftables;
+  final MonsterObjectBuilder? _enemy;
+  final List<int>? _testnestedflatbuffer;
+  final StatObjectBuilder? _testempty;
+  final bool? _testbool;
+  final int? _testhashs32Fnv1;
+  final int? _testhashu32Fnv1;
+  final int? _testhashs64Fnv1;
+  final int? _testhashu64Fnv1;
+  final int? _testhashs32Fnv1a;
+  final int? _testhashu32Fnv1a;
+  final int? _testhashs64Fnv1a;
+  final int? _testhashu64Fnv1a;
+  final List<bool>? _testarrayofbools;
+  final double? _testf;
+  final double? _testf2;
+  final double? _testf3;
+  final List<String>? _testarrayofstring2;
+  final List<AbilityObjectBuilder>? _testarrayofsortedstruct;
+  final List<int>? _flex;
+  final List<TestObjectBuilder>? _test5;
+  final List<int>? _vectorOfLongs;
+  final List<double>? _vectorOfDoubles;
+  final my_game.InParentNamespaceObjectBuilder? _parentNamespaceTest;
+  final List<ReferrableObjectBuilder>? _vectorOfReferrables;
+  final int? _singleWeakReference;
+  final List<int>? _vectorOfWeakReferences;
+  final List<ReferrableObjectBuilder>? _vectorOfStrongReferrables;
+  final int? _coOwningReference;
+  final List<int>? _vectorOfCoOwningReferences;
+  final int? _nonOwningReference;
+  final List<int>? _vectorOfNonOwningReferences;
+  final AnyUniqueAliasesTypeId? _anyUniqueType;
+  final dynamic? _anyUnique;
+  final AnyAmbiguousAliasesTypeId? _anyAmbiguousType;
+  final dynamic? _anyAmbiguous;
+  final List<Color>? _vectorOfEnums;
+  final Race? _signedEnum;
+  final List<int>? _testrequirednestedflatbuffer;
+  final List<StatObjectBuilder>? _scalarKeySortedTables;
 
   MonsterObjectBuilder({
-    Vec3ObjectBuilder pos,
-    int mana,
-    int hp,
-    String name,
-    List<int> inventory,
-    Color color,
-    AnyTypeId testType,
-    dynamic test,
-    List<TestObjectBuilder> test4,
-    List<String> testarrayofstring,
-    List<MonsterObjectBuilder> testarrayoftables,
-    MonsterObjectBuilder enemy,
-    List<int> testnestedflatbuffer,
-    StatObjectBuilder testempty,
-    bool testbool,
-    int testhashs32Fnv1,
-    int testhashu32Fnv1,
-    int testhashs64Fnv1,
-    int testhashu64Fnv1,
-    int testhashs32Fnv1a,
-    int testhashu32Fnv1a,
-    int testhashs64Fnv1a,
-    int testhashu64Fnv1a,
-    List<bool> testarrayofbools,
-    double testf,
-    double testf2,
-    double testf3,
-    List<String> testarrayofstring2,
-    List<AbilityObjectBuilder> testarrayofsortedstruct,
-    List<int> flex,
-    List<TestObjectBuilder> test5,
-    List<int> vectorOfLongs,
-    List<double> vectorOfDoubles,
-    my_game.InParentNamespaceObjectBuilder parentNamespaceTest,
-    List<ReferrableObjectBuilder> vectorOfReferrables,
-    int singleWeakReference,
-    List<int> vectorOfWeakReferences,
-    List<ReferrableObjectBuilder> vectorOfStrongReferrables,
-    int coOwningReference,
-    List<int> vectorOfCoOwningReferences,
-    int nonOwningReference,
-    List<int> vectorOfNonOwningReferences,
-    AnyUniqueAliasesTypeId anyUniqueType,
-    dynamic anyUnique,
-    AnyAmbiguousAliasesTypeId anyAmbiguousType,
-    dynamic anyAmbiguous,
-    List<Color> vectorOfEnums,
-    Race signedEnum,
-    List<int> testrequirednestedflatbuffer,
-    List<StatObjectBuilder> scalarKeySortedTables,
+    Vec3ObjectBuilder? pos,
+    int? mana,
+    int? hp,
+    String? name,
+    List<int>? inventory,
+    Color? color,
+    AnyTypeId? testType,
+    dynamic? test,
+    List<TestObjectBuilder>? test4,
+    List<String>? testarrayofstring,
+    List<MonsterObjectBuilder>? testarrayoftables,
+    MonsterObjectBuilder? enemy,
+    List<int>? testnestedflatbuffer,
+    StatObjectBuilder? testempty,
+    bool? testbool,
+    int? testhashs32Fnv1,
+    int? testhashu32Fnv1,
+    int? testhashs64Fnv1,
+    int? testhashu64Fnv1,
+    int? testhashs32Fnv1a,
+    int? testhashu32Fnv1a,
+    int? testhashs64Fnv1a,
+    int? testhashu64Fnv1a,
+    List<bool>? testarrayofbools,
+    double? testf,
+    double? testf2,
+    double? testf3,
+    List<String>? testarrayofstring2,
+    List<AbilityObjectBuilder>? testarrayofsortedstruct,
+    List<int>? flex,
+    List<TestObjectBuilder>? test5,
+    List<int>? vectorOfLongs,
+    List<double>? vectorOfDoubles,
+    my_game.InParentNamespaceObjectBuilder? parentNamespaceTest,
+    List<ReferrableObjectBuilder>? vectorOfReferrables,
+    int? singleWeakReference,
+    List<int>? vectorOfWeakReferences,
+    List<ReferrableObjectBuilder>? vectorOfStrongReferrables,
+    int? coOwningReference,
+    List<int>? vectorOfCoOwningReferences,
+    int? nonOwningReference,
+    List<int>? vectorOfNonOwningReferences,
+    AnyUniqueAliasesTypeId? anyUniqueType,
+    dynamic? anyUnique,
+    AnyAmbiguousAliasesTypeId? anyAmbiguousType,
+    dynamic? anyAmbiguous,
+    List<Color>? vectorOfEnums,
+    Race? signedEnum,
+    List<int>? testrequirednestedflatbuffer,
+    List<StatObjectBuilder>? scalarKeySortedTables,
   })
       : _pos = pos,
         _mana = mana,
@@ -1870,112 +1793,91 @@ class MonsterObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-    final int nameOffset = fbBuilder.writeString(_name);
-    final int inventoryOffset = _inventory?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(_inventory)
+  int finish(fb.Builder fbBuilder) {
+    final int? nameOffset = fbBuilder.writeString(_name);
+    final int? inventoryOffset = _inventory?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(_inventory!)
         : null;
-    final int testOffset = _test?.getOrCreateOffset(fbBuilder);
-    final int test4Offset = _test4?.isNotEmpty == true
-        ? fbBuilder.writeListOfStructs(_test4)
+    final int? testOffset = _test?.getOrCreateOffset(fbBuilder);
+    final int? test4Offset = _test4?.isNotEmpty == true
+        ? fbBuilder.writeListOfStructs(_test4!)
         : null;
-    final int testarrayofstringOffset = _testarrayofstring?.isNotEmpty == true
-        ? fbBuilder.writeList(_testarrayofstring.map((b) => fbBuilder.writeString(b)).toList())
+    final int? testarrayofstringOffset = _testarrayofstring?.isNotEmpty == true
+        ? fbBuilder.writeList(_testarrayofstring!.map((b) => fbBuilder.writeString(b)!).toList())
         : null;
-    final int testarrayoftablesOffset = _testarrayoftables?.isNotEmpty == true
-        ? fbBuilder.writeList(_testarrayoftables.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
+    final int? testarrayoftablesOffset = _testarrayoftables?.isNotEmpty == true
+        ? fbBuilder.writeList(_testarrayoftables!.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
         : null;
-    final int enemyOffset = _enemy?.getOrCreateOffset(fbBuilder);
-    final int testnestedflatbufferOffset = _testnestedflatbuffer?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(_testnestedflatbuffer)
+    final int? enemyOffset = _enemy?.getOrCreateOffset(fbBuilder);
+    final int? testnestedflatbufferOffset = _testnestedflatbuffer?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(_testnestedflatbuffer!)
         : null;
-    final int testemptyOffset = _testempty?.getOrCreateOffset(fbBuilder);
-    final int testarrayofboolsOffset = _testarrayofbools?.isNotEmpty == true
-        ? fbBuilder.writeListBool(_testarrayofbools)
+    final int? testemptyOffset = _testempty?.getOrCreateOffset(fbBuilder);
+    final int? testarrayofboolsOffset = _testarrayofbools?.isNotEmpty == true
+        ? fbBuilder.writeListBool(_testarrayofbools!)
         : null;
-    final int testarrayofstring2Offset = _testarrayofstring2?.isNotEmpty == true
-        ? fbBuilder.writeList(_testarrayofstring2.map((b) => fbBuilder.writeString(b)).toList())
+    final int? testarrayofstring2Offset = _testarrayofstring2?.isNotEmpty == true
+        ? fbBuilder.writeList(_testarrayofstring2!.map((b) => fbBuilder.writeString(b)!).toList())
         : null;
-    final int testarrayofsortedstructOffset = _testarrayofsortedstruct?.isNotEmpty == true
-        ? fbBuilder.writeListOfStructs(_testarrayofsortedstruct)
+    final int? testarrayofsortedstructOffset = _testarrayofsortedstruct?.isNotEmpty == true
+        ? fbBuilder.writeListOfStructs(_testarrayofsortedstruct!)
         : null;
-    final int flexOffset = _flex?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(_flex)
+    final int? flexOffset = _flex?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(_flex!)
         : null;
-    final int test5Offset = _test5?.isNotEmpty == true
-        ? fbBuilder.writeListOfStructs(_test5)
+    final int? test5Offset = _test5?.isNotEmpty == true
+        ? fbBuilder.writeListOfStructs(_test5!)
         : null;
-    final int vectorOfLongsOffset = _vectorOfLongs?.isNotEmpty == true
-        ? fbBuilder.writeListInt64(_vectorOfLongs)
+    final int? vectorOfLongsOffset = _vectorOfLongs?.isNotEmpty == true
+        ? fbBuilder.writeListInt64(_vectorOfLongs!)
         : null;
-    final int vectorOfDoublesOffset = _vectorOfDoubles?.isNotEmpty == true
-        ? fbBuilder.writeListFloat64(_vectorOfDoubles)
+    final int? vectorOfDoublesOffset = _vectorOfDoubles?.isNotEmpty == true
+        ? fbBuilder.writeListFloat64(_vectorOfDoubles!)
         : null;
-    final int parentNamespaceTestOffset = _parentNamespaceTest?.getOrCreateOffset(fbBuilder);
-    final int vectorOfReferrablesOffset = _vectorOfReferrables?.isNotEmpty == true
-        ? fbBuilder.writeList(_vectorOfReferrables.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
+    final int? parentNamespaceTestOffset = _parentNamespaceTest?.getOrCreateOffset(fbBuilder);
+    final int? vectorOfReferrablesOffset = _vectorOfReferrables?.isNotEmpty == true
+        ? fbBuilder.writeList(_vectorOfReferrables!.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
         : null;
-    final int vectorOfWeakReferencesOffset = _vectorOfWeakReferences?.isNotEmpty == true
-        ? fbBuilder.writeListUint64(_vectorOfWeakReferences)
+    final int? vectorOfWeakReferencesOffset = _vectorOfWeakReferences?.isNotEmpty == true
+        ? fbBuilder.writeListUint64(_vectorOfWeakReferences!)
         : null;
-    final int vectorOfStrongReferrablesOffset = _vectorOfStrongReferrables?.isNotEmpty == true
-        ? fbBuilder.writeList(_vectorOfStrongReferrables.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
+    final int? vectorOfStrongReferrablesOffset = _vectorOfStrongReferrables?.isNotEmpty == true
+        ? fbBuilder.writeList(_vectorOfStrongReferrables!.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
         : null;
-    final int vectorOfCoOwningReferencesOffset = _vectorOfCoOwningReferences?.isNotEmpty == true
-        ? fbBuilder.writeListUint64(_vectorOfCoOwningReferences)
+    final int? vectorOfCoOwningReferencesOffset = _vectorOfCoOwningReferences?.isNotEmpty == true
+        ? fbBuilder.writeListUint64(_vectorOfCoOwningReferences!)
         : null;
-    final int vectorOfNonOwningReferencesOffset = _vectorOfNonOwningReferences?.isNotEmpty == true
-        ? fbBuilder.writeListUint64(_vectorOfNonOwningReferences)
+    final int? vectorOfNonOwningReferencesOffset = _vectorOfNonOwningReferences?.isNotEmpty == true
+        ? fbBuilder.writeListUint64(_vectorOfNonOwningReferences!)
         : null;
-    final int anyUniqueOffset = _anyUnique?.getOrCreateOffset(fbBuilder);
-    final int anyAmbiguousOffset = _anyAmbiguous?.getOrCreateOffset(fbBuilder);
-    final int vectorOfEnumsOffset = _vectorOfEnums?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(_vectorOfEnums.map((f) => f.value).toList())
+    final int? anyUniqueOffset = _anyUnique?.getOrCreateOffset(fbBuilder);
+    final int? anyAmbiguousOffset = _anyAmbiguous?.getOrCreateOffset(fbBuilder);
+    final int? vectorOfEnumsOffset = _vectorOfEnums?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(_vectorOfEnums!.map((f) => f.value).toList())
         : null;
-    final int testrequirednestedflatbufferOffset = _testrequirednestedflatbuffer?.isNotEmpty == true
-        ? fbBuilder.writeListUint8(_testrequirednestedflatbuffer)
+    final int? testrequirednestedflatbufferOffset = _testrequirednestedflatbuffer?.isNotEmpty == true
+        ? fbBuilder.writeListUint8(_testrequirednestedflatbuffer!)
         : null;
-    final int scalarKeySortedTablesOffset = _scalarKeySortedTables?.isNotEmpty == true
-        ? fbBuilder.writeList(_scalarKeySortedTables.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
+    final int? scalarKeySortedTablesOffset = _scalarKeySortedTables?.isNotEmpty == true
+        ? fbBuilder.writeList(_scalarKeySortedTables!.map((b) => b.getOrCreateOffset(fbBuilder)).toList())
         : null;
-
     fbBuilder.startTable();
     if (_pos != null) {
-      fbBuilder.addStruct(0, _pos.finish(fbBuilder));
+      fbBuilder.addStruct(0, _pos!.finish(fbBuilder));
     }
     fbBuilder.addInt16(1, _mana);
     fbBuilder.addInt16(2, _hp);
-    if (nameOffset != null) {
-      fbBuilder.addOffset(3, nameOffset);
-    }
-    if (inventoryOffset != null) {
-      fbBuilder.addOffset(5, inventoryOffset);
-    }
+    fbBuilder.addOffset(3, nameOffset);
+    fbBuilder.addOffset(5, inventoryOffset);
     fbBuilder.addUint8(6, _color?.value);
     fbBuilder.addUint8(7, _testType?.value);
-    if (testOffset != null) {
-      fbBuilder.addOffset(8, testOffset);
-    }
-    if (test4Offset != null) {
-      fbBuilder.addOffset(9, test4Offset);
-    }
-    if (testarrayofstringOffset != null) {
-      fbBuilder.addOffset(10, testarrayofstringOffset);
-    }
-    if (testarrayoftablesOffset != null) {
-      fbBuilder.addOffset(11, testarrayoftablesOffset);
-    }
-    if (enemyOffset != null) {
-      fbBuilder.addOffset(12, enemyOffset);
-    }
-    if (testnestedflatbufferOffset != null) {
-      fbBuilder.addOffset(13, testnestedflatbufferOffset);
-    }
-    if (testemptyOffset != null) {
-      fbBuilder.addOffset(14, testemptyOffset);
-    }
+    fbBuilder.addOffset(8, testOffset);
+    fbBuilder.addOffset(9, test4Offset);
+    fbBuilder.addOffset(10, testarrayofstringOffset);
+    fbBuilder.addOffset(11, testarrayoftablesOffset);
+    fbBuilder.addOffset(12, enemyOffset);
+    fbBuilder.addOffset(13, testnestedflatbufferOffset);
+    fbBuilder.addOffset(14, testemptyOffset);
     fbBuilder.addBool(15, _testbool);
     fbBuilder.addInt32(16, _testhashs32Fnv1);
     fbBuilder.addUint32(17, _testhashu32Fnv1);
@@ -1985,75 +1887,39 @@ class MonsterObjectBuilder extends fb.ObjectBuilder {
     fbBuilder.addUint32(21, _testhashu32Fnv1a);
     fbBuilder.addInt64(22, _testhashs64Fnv1a);
     fbBuilder.addUint64(23, _testhashu64Fnv1a);
-    if (testarrayofboolsOffset != null) {
-      fbBuilder.addOffset(24, testarrayofboolsOffset);
-    }
+    fbBuilder.addOffset(24, testarrayofboolsOffset);
     fbBuilder.addFloat32(25, _testf);
     fbBuilder.addFloat32(26, _testf2);
     fbBuilder.addFloat32(27, _testf3);
-    if (testarrayofstring2Offset != null) {
-      fbBuilder.addOffset(28, testarrayofstring2Offset);
-    }
-    if (testarrayofsortedstructOffset != null) {
-      fbBuilder.addOffset(29, testarrayofsortedstructOffset);
-    }
-    if (flexOffset != null) {
-      fbBuilder.addOffset(30, flexOffset);
-    }
-    if (test5Offset != null) {
-      fbBuilder.addOffset(31, test5Offset);
-    }
-    if (vectorOfLongsOffset != null) {
-      fbBuilder.addOffset(32, vectorOfLongsOffset);
-    }
-    if (vectorOfDoublesOffset != null) {
-      fbBuilder.addOffset(33, vectorOfDoublesOffset);
-    }
-    if (parentNamespaceTestOffset != null) {
-      fbBuilder.addOffset(34, parentNamespaceTestOffset);
-    }
-    if (vectorOfReferrablesOffset != null) {
-      fbBuilder.addOffset(35, vectorOfReferrablesOffset);
-    }
+    fbBuilder.addOffset(28, testarrayofstring2Offset);
+    fbBuilder.addOffset(29, testarrayofsortedstructOffset);
+    fbBuilder.addOffset(30, flexOffset);
+    fbBuilder.addOffset(31, test5Offset);
+    fbBuilder.addOffset(32, vectorOfLongsOffset);
+    fbBuilder.addOffset(33, vectorOfDoublesOffset);
+    fbBuilder.addOffset(34, parentNamespaceTestOffset);
+    fbBuilder.addOffset(35, vectorOfReferrablesOffset);
     fbBuilder.addUint64(36, _singleWeakReference);
-    if (vectorOfWeakReferencesOffset != null) {
-      fbBuilder.addOffset(37, vectorOfWeakReferencesOffset);
-    }
-    if (vectorOfStrongReferrablesOffset != null) {
-      fbBuilder.addOffset(38, vectorOfStrongReferrablesOffset);
-    }
+    fbBuilder.addOffset(37, vectorOfWeakReferencesOffset);
+    fbBuilder.addOffset(38, vectorOfStrongReferrablesOffset);
     fbBuilder.addUint64(39, _coOwningReference);
-    if (vectorOfCoOwningReferencesOffset != null) {
-      fbBuilder.addOffset(40, vectorOfCoOwningReferencesOffset);
-    }
+    fbBuilder.addOffset(40, vectorOfCoOwningReferencesOffset);
     fbBuilder.addUint64(41, _nonOwningReference);
-    if (vectorOfNonOwningReferencesOffset != null) {
-      fbBuilder.addOffset(42, vectorOfNonOwningReferencesOffset);
-    }
+    fbBuilder.addOffset(42, vectorOfNonOwningReferencesOffset);
     fbBuilder.addUint8(43, _anyUniqueType?.value);
-    if (anyUniqueOffset != null) {
-      fbBuilder.addOffset(44, anyUniqueOffset);
-    }
+    fbBuilder.addOffset(44, anyUniqueOffset);
     fbBuilder.addUint8(45, _anyAmbiguousType?.value);
-    if (anyAmbiguousOffset != null) {
-      fbBuilder.addOffset(46, anyAmbiguousOffset);
-    }
-    if (vectorOfEnumsOffset != null) {
-      fbBuilder.addOffset(47, vectorOfEnumsOffset);
-    }
+    fbBuilder.addOffset(46, anyAmbiguousOffset);
+    fbBuilder.addOffset(47, vectorOfEnumsOffset);
     fbBuilder.addInt8(48, _signedEnum?.value);
-    if (testrequirednestedflatbufferOffset != null) {
-      fbBuilder.addOffset(49, testrequirednestedflatbufferOffset);
-    }
-    if (scalarKeySortedTablesOffset != null) {
-      fbBuilder.addOffset(50, scalarKeySortedTablesOffset);
-    }
+    fbBuilder.addOffset(49, testrequirednestedflatbufferOffset);
+    fbBuilder.addOffset(50, scalarKeySortedTablesOffset);
     return fbBuilder.endTable();
   }
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
@@ -2081,8 +1947,8 @@ class TypeAliases {
   int get u64 => const fb.Uint64Reader().vTableGet(_bc, _bcOffset, 18, 0);
   double get f32 => const fb.Float32Reader().vTableGet(_bc, _bcOffset, 20, 0.0);
   double get f64 => const fb.Float64Reader().vTableGet(_bc, _bcOffset, 22, 0.0);
-  List<int> get v8 => const fb.ListReader<int>(const fb.Int8Reader()).vTableGet(_bc, _bcOffset, 24, null);
-  List<double> get vf64 => const fb.ListReader<double>(const fb.Float64Reader()).vTableGet(_bc, _bcOffset, 26, null);
+  List<int>? get v8 => const fb.ListReader<int>(const fb.Int8Reader()).vTableGetNullable(_bc, _bcOffset, 24);
+  List<double>? get vf64 => const fb.ListReader<double>(const fb.Float64Reader()).vTableGetNullable(_bc, _bcOffset, 26);
 
   @override
   String toString() {
@@ -2103,7 +1969,7 @@ class TypeAliases {
       v8: v8,
       vf64: vf64);
 
-  static int pack(fb.Builder fbBuilder, TypeAliasesT object) {
+  static int pack(fb.Builder fbBuilder, TypeAliasesT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -2120,32 +1986,30 @@ class TypeAliasesT {
   int u64;
   double f32;
   double f64;
-  List<int> v8;
-  List<double> vf64;
+  List<int>? v8;
+  List<double>? vf64;
 
   TypeAliasesT({
-      this.i8,
-      this.u8,
-      this.i16,
-      this.u16,
-      this.i32,
-      this.u32,
-      this.i64,
-      this.u64,
-      this.f32,
-      this.f64,
+      this.i8 = 0,
+      this.u8 = 0,
+      this.i16 = 0,
+      this.u16 = 0,
+      this.i32 = 0,
+      this.u32 = 0,
+      this.i64 = 0,
+      this.u64 = 0,
+      this.f32 = 0.0,
+      this.f64 = 0.0,
       this.v8,
       this.vf64});
 
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-    final int v8Offset = v8?.isNotEmpty == true
-        ? fbBuilder.writeListInt8(v8)
+    final int? v8Offset = v8?.isNotEmpty == true
+        ? fbBuilder.writeListInt8(v8!)
         : null;
-    final int vf64Offset = vf64?.isNotEmpty == true
-        ? fbBuilder.writeListFloat64(vf64)
+    final int? vf64Offset = vf64?.isNotEmpty == true
+        ? fbBuilder.writeListFloat64(vf64!)
         : null;
-
     fbBuilder.startTable();
     fbBuilder.addInt8(0, i8);
     fbBuilder.addUint8(1, u8);
@@ -2157,12 +2021,8 @@ class TypeAliasesT {
     fbBuilder.addUint64(7, u64);
     fbBuilder.addFloat32(8, f32);
     fbBuilder.addFloat64(9, f64);
-    if (v8Offset != null) {
-      fbBuilder.addOffset(10, v8Offset);
-    }
-    if (vf64Offset != null) {
-      fbBuilder.addOffset(11, vf64Offset);
-    }
+    fbBuilder.addOffset(10, v8Offset);
+    fbBuilder.addOffset(11, vf64Offset);
     return fbBuilder.endTable();
   }
 
@@ -2181,9 +2041,7 @@ class _TypeAliasesReader extends fb.TableReader<TypeAliases> {
 }
 
 class TypeAliasesBuilder {
-  TypeAliasesBuilder(this.fbBuilder) {
-    assert(fbBuilder != null);
-  }
+  TypeAliasesBuilder(this.fbBuilder) {}
 
   final fb.Builder fbBuilder;
 
@@ -2191,51 +2049,51 @@ class TypeAliasesBuilder {
     fbBuilder.startTable();
   }
 
-  int addI8(int i8) {
+  int addI8(int? i8) {
     fbBuilder.addInt8(0, i8);
     return fbBuilder.offset;
   }
-  int addU8(int u8) {
+  int addU8(int? u8) {
     fbBuilder.addUint8(1, u8);
     return fbBuilder.offset;
   }
-  int addI16(int i16) {
+  int addI16(int? i16) {
     fbBuilder.addInt16(2, i16);
     return fbBuilder.offset;
   }
-  int addU16(int u16) {
+  int addU16(int? u16) {
     fbBuilder.addUint16(3, u16);
     return fbBuilder.offset;
   }
-  int addI32(int i32) {
+  int addI32(int? i32) {
     fbBuilder.addInt32(4, i32);
     return fbBuilder.offset;
   }
-  int addU32(int u32) {
+  int addU32(int? u32) {
     fbBuilder.addUint32(5, u32);
     return fbBuilder.offset;
   }
-  int addI64(int i64) {
+  int addI64(int? i64) {
     fbBuilder.addInt64(6, i64);
     return fbBuilder.offset;
   }
-  int addU64(int u64) {
+  int addU64(int? u64) {
     fbBuilder.addUint64(7, u64);
     return fbBuilder.offset;
   }
-  int addF32(double f32) {
+  int addF32(double? f32) {
     fbBuilder.addFloat32(8, f32);
     return fbBuilder.offset;
   }
-  int addF64(double f64) {
+  int addF64(double? f64) {
     fbBuilder.addFloat64(9, f64);
     return fbBuilder.offset;
   }
-  int addV8Offset(int offset) {
+  int addV8Offset(int? offset) {
     fbBuilder.addOffset(10, offset);
     return fbBuilder.offset;
   }
-  int addVf64Offset(int offset) {
+  int addVf64Offset(int? offset) {
     fbBuilder.addOffset(11, offset);
     return fbBuilder.offset;
   }
@@ -2246,32 +2104,32 @@ class TypeAliasesBuilder {
 }
 
 class TypeAliasesObjectBuilder extends fb.ObjectBuilder {
-  final int _i8;
-  final int _u8;
-  final int _i16;
-  final int _u16;
-  final int _i32;
-  final int _u32;
-  final int _i64;
-  final int _u64;
-  final double _f32;
-  final double _f64;
-  final List<int> _v8;
-  final List<double> _vf64;
+  final int? _i8;
+  final int? _u8;
+  final int? _i16;
+  final int? _u16;
+  final int? _i32;
+  final int? _u32;
+  final int? _i64;
+  final int? _u64;
+  final double? _f32;
+  final double? _f64;
+  final List<int>? _v8;
+  final List<double>? _vf64;
 
   TypeAliasesObjectBuilder({
-    int i8,
-    int u8,
-    int i16,
-    int u16,
-    int i32,
-    int u32,
-    int i64,
-    int u64,
-    double f32,
-    double f64,
-    List<int> v8,
-    List<double> vf64,
+    int? i8,
+    int? u8,
+    int? i16,
+    int? u16,
+    int? i32,
+    int? u32,
+    int? i64,
+    int? u64,
+    double? f32,
+    double? f64,
+    List<int>? v8,
+    List<double>? vf64,
   })
       : _i8 = i8,
         _u8 = u8,
@@ -2288,16 +2146,13 @@ class TypeAliasesObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-    final int v8Offset = _v8?.isNotEmpty == true
-        ? fbBuilder.writeListInt8(_v8)
+  int finish(fb.Builder fbBuilder) {
+    final int? v8Offset = _v8?.isNotEmpty == true
+        ? fbBuilder.writeListInt8(_v8!)
         : null;
-    final int vf64Offset = _vf64?.isNotEmpty == true
-        ? fbBuilder.writeListFloat64(_vf64)
+    final int? vf64Offset = _vf64?.isNotEmpty == true
+        ? fbBuilder.writeListFloat64(_vf64!)
         : null;
-
     fbBuilder.startTable();
     fbBuilder.addInt8(0, _i8);
     fbBuilder.addUint8(1, _u8);
@@ -2309,18 +2164,14 @@ class TypeAliasesObjectBuilder extends fb.ObjectBuilder {
     fbBuilder.addUint64(7, _u64);
     fbBuilder.addFloat32(8, _f32);
     fbBuilder.addFloat64(9, _f64);
-    if (v8Offset != null) {
-      fbBuilder.addOffset(10, v8Offset);
-    }
-    if (vf64Offset != null) {
-      fbBuilder.addOffset(11, vf64Offset);
-    }
+    fbBuilder.addOffset(10, v8Offset);
+    fbBuilder.addOffset(11, vf64Offset);
     return fbBuilder.endTable();
   }
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);
diff --git a/dart/test/monster_test_my_game_generated.dart b/dart/test/monster_test_my_game_generated.dart
index d53550d1..146c4017 100644
--- a/dart/test/monster_test_my_game_generated.dart
+++ b/dart/test/monster_test_my_game_generated.dart
@@ -1,5 +1,5 @@
 // automatically generated by the FlatBuffers compiler, do not modify
-// ignore_for_file: unused_import, unused_field, unused_local_variable
+// ignore_for_file: unused_import, unused_field, unused_element, unused_local_variable
 
 library my_game;
 
@@ -29,7 +29,7 @@ class InParentNamespace {
 
   InParentNamespaceT unpack() => InParentNamespaceT();
 
-  static int pack(fb.Builder fbBuilder, InParentNamespaceT object) {
+  static int pack(fb.Builder fbBuilder, InParentNamespaceT? object) {
     if (object == null) return 0;
     return object.pack(fbBuilder);
   }
@@ -37,8 +37,6 @@ class InParentNamespace {
 
 class InParentNamespaceT {
   int pack(fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
     fbBuilder.startTable();
     return fbBuilder.endTable();
   }
@@ -63,17 +61,14 @@ class InParentNamespaceObjectBuilder extends fb.ObjectBuilder {
 
   /// Finish building, and store into the [fbBuilder].
   @override
-  int finish(
-    fb.Builder fbBuilder) {
-    assert(fbBuilder != null);
-
+  int finish(fb.Builder fbBuilder) {
     fbBuilder.startTable();
     return fbBuilder.endTable();
   }
 
   /// Convenience method to serialize to byte list.
   @override
-  Uint8List toBytes([String fileIdentifier]) {
+  Uint8List toBytes([String? fileIdentifier]) {
     fb.Builder fbBuilder = new fb.Builder();
     int offset = finish(fbBuilder);
     return fbBuilder.finish(offset, fileIdentifier);