Thumbnail constructor Null safety

1. cloudinary_url_gen
2. crop
3. Thumbnail
4. Thumbnail constructor

Thumbnail class

1. Constructors
2. Thumbnail
3. Properties
4. actionType
5. dimensions
6. hashCode
7. regionRelative
8. relative
9. runtimeType
10. Methods
11. aspectRatio
12. gravity
13. height
14. noSuchMethod
15. params
16. toString
17. width
18. x
19. y
20. zoom
21. Operators
22. operator ==