EntityStateUpdate_Kind constructor Null safety

1. spine_client
2. subscription.pb
3. EntityStateUpdate_Kind
4. EntityStateUpdate_Kind const constructor

EntityStateUpdate_Kind enum

1. Constructors
2. EntityStateUpdate_Kind
3. Values
4. state
5. noLongerMatching
6. notSet
7. Properties
8. hashCode
9. index
10. runtimeType
11. Methods
12. noSuchMethod
13. toString
14. Operators
15. operator ==
16. Constants
17. values