toJson method
Implementation
@override
Map<String, dynamic> toJson() {
final Map<String, dynamic> json = super.toJson();
json['image_old'] = imageOld.toJson();
json['image_new'] = imageNew.toJson();
json['image_caption_old'] = captionOld.toJson();
json['image_caption_new'] = captionNew.toJson();
return json;
}