Dart APIunself_modelStructStruct.fromJson factory constructor Struct.fromJson constructor Null safety Struct.fromJson(Map<String, dynamic> json ) Implementation factory Struct.fromJson(Map<String, dynamic> json) = _$Struct.fromJson; unself_model unself_model Struct Struct.fromJson factory constructor Struct class Constructors Struct fromJson Properties copyWith definition extra hashCode name runtimeType Methods map mapOrNull maybeMap maybeWhen noSuchMethod toJson toString when whenOrNull Operators operator ==