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Support using non-nullable JsonConverter on nullable properties (#1136)
fixes #822
1 parent 5dbb1b2 commit 09cca32

18 files changed

+426
-16
lines changed

‎json_serializable/CHANGELOG.md‎

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@@ -1,3 +1,8 @@
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## 6.3.0-dev
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- Added support for using a `JsonConverter<MyClass, Object>` on properties
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of type `MyClass?`. ([#822](https://github.com/google/json_serializable.dart/issues/822))
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## 6.2.0
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- Added support for the new `FieldRename.screamingSnake` field in

‎json_serializable/lib/src/type_helpers/json_converter_helper.dart‎

Lines changed: 84 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -32,6 +32,24 @@ class JsonConverterHelper extends TypeHelper {
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return null;
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}
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35+
if (!converter.fieldType.isNullableType && targetType.isNullableType) {
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const converterToJsonName = r'_$JsonConverterToJson';
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context.addMember('''
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Json? $converterToJsonName<Json, Value>(
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Value? value,
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Json? Function(Value value) toJson,
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) => ${ifNullOrElse('value', 'null', 'toJson(value)')};
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''');
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return _nullableJsonConverterLambdaResult(
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converter,
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name: converterToJsonName,
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targetType: targetType,
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expression: expression,
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callback: '${converter.accessString}.toJson',
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);
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}
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3553
return LambdaResult(expression, '${converter.accessString}.toJson');
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}
3755

@@ -49,6 +67,24 @@ class JsonConverterHelper extends TypeHelper {
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final asContent = asStatement(converter.jsonType);
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70+
if (!converter.jsonType.isNullableType && targetType.isNullableType) {
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const converterFromJsonName = r'_$JsonConverterFromJson';
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context.addMember('''
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Value? $converterFromJsonName<Json, Value>(
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Object? json,
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Value? Function(Json json) fromJson,
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) => ${ifNullOrElse('json', 'null', 'fromJson(json as Json)')};
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''');
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return _nullableJsonConverterLambdaResult(
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converter,
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name: converterFromJsonName,
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targetType: targetType,
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expression: expression,
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callback: '${converter.accessString}.fromJson',
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);
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}
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5288
return LambdaResult(
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expression,
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'${converter.accessString}.fromJson',
@@ -57,24 +93,51 @@ class JsonConverterHelper extends TypeHelper {
5793
}
5894
}
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96+
String _nullableJsonConverterLambdaResult(
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_JsonConvertData converter, {
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required String name,
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required DartType targetType,
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required String expression,
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required String callback,
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}) {
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final jsonDisplayString = typeToCode(converter.jsonType);
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final fieldTypeDisplayString = converter.isGeneric
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? typeToCode(targetType)
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: typeToCode(converter.fieldType);
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108+
return '$name<$jsonDisplayString, $fieldTypeDisplayString>('
109+
'$expression, $callback)';
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}
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60112
class _JsonConvertData {
61113
final String accessString;
62114
final DartType jsonType;
115+
final DartType fieldType;
116+
final bool isGeneric;
63117

64118
_JsonConvertData.className(
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String className,
66120
String accessor,
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this.jsonType,
68-
) : accessString = 'const $className${_withAccessor(accessor)}()';
122+
this.fieldType,
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) : accessString = 'const $className${_withAccessor(accessor)}()',
124+
isGeneric = false;
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70126
_JsonConvertData.genericClass(
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String className,
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String genericTypeArg,
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String accessor,
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this.jsonType,
75-
) : accessString = '$className<$genericTypeArg>${_withAccessor(accessor)}()';
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this.fieldType,
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) : accessString =
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'$className<$genericTypeArg>${_withAccessor(accessor)}()',
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isGeneric = true;
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77-
_JsonConvertData.propertyAccess(this.accessString, this.jsonType);
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_JsonConvertData.propertyAccess(
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this.accessString,
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this.jsonType,
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this.fieldType,
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) : isGeneric = false;
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79142
static String _withAccessor(String accessor) =>
80143
accessor.isEmpty ? '' : '.$accessor';
@@ -127,7 +190,11 @@ _JsonConvertData? _typeConverterFrom(
127190
accessString = '${enclosing.name}.$accessString';
128191
}
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130-
return _JsonConvertData.propertyAccess(accessString, match.jsonType);
193+
return _JsonConvertData.propertyAccess(
194+
accessString,
195+
match.jsonType,
196+
match.fieldType,
197+
);
131198
}
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133200
final reviver = ConstantReader(match.annotation).revive();
@@ -145,18 +212,21 @@ _JsonConvertData? _typeConverterFrom(
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match.genericTypeArg!,
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reviver.accessor,
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match.jsonType,
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match.fieldType,
148216
);
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}
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return _JsonConvertData.className(
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match.annotation.type!.element!.name!,
153221
reviver.accessor,
154222
match.jsonType,
223+
match.fieldType,
155224
);
156225
}
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158227
class _ConverterMatch {
159228
final DartObject annotation;
229+
final DartType fieldType;
160230
final DartType jsonType;
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final ElementAnnotation elementAnnotation;
162232
final String? genericTypeArg;
@@ -166,6 +236,7 @@ class _ConverterMatch {
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this.annotation,
167237
this.jsonType,
168238
this.genericTypeArg,
239+
this.fieldType,
169240
);
170241
}
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@@ -191,9 +262,15 @@ _ConverterMatch? _compatibleMatch(
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192263
final fieldType = jsonConverterSuper.typeArguments[0];
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194-
if (fieldType == targetType) {
265+
// Allow assigning T to T?
266+
if (fieldType == targetType || fieldType == targetType.promoteNonNullable()) {
195267
return _ConverterMatch(
196-
annotation, constantValue, jsonConverterSuper.typeArguments[1], null);
268+
annotation,
269+
constantValue,
270+
jsonConverterSuper.typeArguments[1],
271+
null,
272+
fieldType,
273+
);
197274
}
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199276
if (fieldType is TypeParameterType && targetType is TypeParameterType) {
@@ -212,6 +289,7 @@ _ConverterMatch? _compatibleMatch(
212289
constantValue,
213290
jsonConverterSuper.typeArguments[1],
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'${targetType.element.name}${targetType.isNullableType ? '?' : ''}',
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fieldType,
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);
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}
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‎json_serializable/pubspec.yaml‎

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@@ -1,5 +1,5 @@
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name: json_serializable
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version: 6.2.0
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version: 6.3.0-dev
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description: >-
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Automatically generate code for converting to and from JSON by annotating
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Dart classes.

‎json_serializable/test/generic_files/generic_class.g.dart‎

Lines changed: 20 additions & 6 deletions
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‎json_serializable/test/json_serializable_test.dart‎

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@@ -85,6 +85,7 @@ const _expectedAnnotatedTests = {
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'JsonConverterCtorParams',
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'JsonConverterDuplicateAnnotations',
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'JsonConverterNamedCtor',
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'JsonConverterNullableToNonNullable',
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'JsonConverterOnGetter',
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'JsonConverterWithBadTypeArg',
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'JsonValueValid',

‎json_serializable/test/kitchen_sink/kitchen_sink.dart‎

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@@ -66,9 +66,13 @@ class _Factory implements k.KitchenSinkFactory<String, dynamic> {
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[],
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BigInt.zero,
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{},
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BigInt.zero,
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{},
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TrivialNumber(0),
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{},
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DateTime.fromMillisecondsSinceEpoch(0),
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TrivialNumber(0),
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{},
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);
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7478
k.JsonConverterTestClass jsonConverterFromJson(Map<String, dynamic> json) =>
@@ -203,9 +207,13 @@ class JsonConverterTestClass implements k.JsonConverterTestClass {
203207
this.durationList,
204208
this.bigInt,
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this.bigIntMap,
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this.nullableBigInt,
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this.nullableBigIntMap,
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this.numberSilly,
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this.numberSillySet,
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this.dateTime,
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this.nullableNumberSilly,
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this.nullableNumberSillySet,
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);
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211219
factory JsonConverterTestClass.fromJson(Map<String, dynamic> json) =>
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BigInt bigInt;
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Map<String, BigInt> bigIntMap;
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BigInt? nullableBigInt;
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Map<String, BigInt?> nullableBigIntMap;
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TrivialNumber numberSilly;
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Set<TrivialNumber> numberSillySet;
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225236
DateTime? dateTime;
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TrivialNumber? nullableNumberSilly;
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Set<TrivialNumber?> nullableNumberSillySet;
226240
}
227241

228242
@JsonSerializable()

‎json_serializable/test/kitchen_sink/kitchen_sink.g.dart‎

Lines changed: 37 additions & 0 deletions
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‎json_serializable/test/kitchen_sink/kitchen_sink.g_any_map.dart‎

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@@ -65,9 +65,13 @@ class _Factory implements k.KitchenSinkFactory<dynamic, dynamic> {
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[],
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BigInt.zero,
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{},
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BigInt.zero,
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{},
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TrivialNumber(0),
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{},
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DateTime.fromMillisecondsSinceEpoch(0),
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TrivialNumber(0),
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{},
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);
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7377
k.JsonConverterTestClass jsonConverterFromJson(Map<String, dynamic> json) =>
@@ -205,9 +209,13 @@ class JsonConverterTestClass implements k.JsonConverterTestClass {
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this.durationList,
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this.bigInt,
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this.bigIntMap,
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this.nullableBigInt,
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this.nullableBigIntMap,
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this.numberSilly,
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this.numberSillySet,
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this.dateTime,
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this.nullableNumberSilly,
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this.nullableNumberSillySet,
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);
212220

213221
factory JsonConverterTestClass.fromJson(Map<String, dynamic> json) =>
@@ -221,10 +229,16 @@ class JsonConverterTestClass implements k.JsonConverterTestClass {
221229
BigInt bigInt;
222230
Map<String, BigInt> bigIntMap;
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232+
BigInt? nullableBigInt;
233+
Map<String, BigInt?> nullableBigIntMap;
234+
224235
TrivialNumber numberSilly;
225236
Set<TrivialNumber> numberSillySet;
226237

227238
DateTime? dateTime;
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240+
TrivialNumber? nullableNumberSilly;
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Set<TrivialNumber?> nullableNumberSillySet;
228242
}
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230244
@JsonSerializable(

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