import 'package:json_annotation/json_annotation.dart'; part 'container_size.g.dart'; @JsonSerializable() class ContainerSize { double? width; double? height; ContainerSize({this.width, this.height}); factory ContainerSize.fromJson(Map json) { return _$ContainerSizeFromJson(json); } Map toJson() => _$ContainerSizeToJson(this); }