Success_Exhaust constructor Null safety

1. spine_client
2. dispatching.pb
3. Success_Exhaust
4. Success_Exhaust const constructor

Success_Exhaust enum

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