SystemMessageStatus constructor Null safety

1. nim_core
2. nim_core
3. SystemMessageStatus
4. SystemMessageStatus const constructor

SystemMessageStatus enum

1. Constructors
2. SystemMessageStatus
3. Values
4. init
5. passed
6. declined
7. ignored
8. expired
9. extension1
10. extension2
11. extension3
12. extension4
13. extension5
14. Properties
15. hashCode
16. index
17. runtimeType
18. Methods
19. noSuchMethod
20. toString
21. Operators
22. operator ==
23. Constants
24. values