GetPlaylistReason constructor Null safety

1. iapetus
2. iapetus_data
3. GetPlaylistReason
4. GetPlaylistReason const constructor

GetPlaylistReason enum

1. Constructors
2. GetPlaylistReason
3. Values
4. normal
5. skip
6. thumbDown
7. error
8. stillListening
9. upgrade
10. Properties
11. hashCode
12. index
13. runtimeType
14. Methods
15. noSuchMethod
16. toString
17. Operators
18. operator ==
19. Constants
20. values