PhotoLikeDataStorage constructor Null safety

1. next_photo
2. features
3. PhotoLikeDataStorage
4. PhotoLikeDataStorage constructor

PhotoLikeDataStorage class

1. Constructors
2. PhotoLikeDataStorage
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. getPhotoLike
8. noSuchMethod
9. setPhotoLike
10. toString
11. Operators
12. operator ==