OperationsServiceBase constructor Null safety

1. spine_client
2. operations.pbserver
3. OperationsServiceBase
4. OperationsServiceBase constructor

OperationsServiceBase class

1. Constructors
2. OperationsServiceBase
3. Properties
4. $json
5. $messageJson
6. hashCode
7. runtimeType
8. Methods
9. cancelOperation
10. createRequest
11. deleteOperation
12. getOperation
13. handleCall
14. listOperations
15. noSuchMethod
16. toString
17. waitOperation
18. Operators
19. operator ==