SystemMessageType constructor Null safety

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

SystemMessageType enum

1. Constructors
2. SystemMessageType
3. Values
4. undefined
5. applyJoinTeam
6. rejectTeamApply
7. teamInvite
8. declineTeamInvite
9. addFriend
10. superTeamApply
11. superTeamApplyReject
12. superTeamInvite
13. superTeamInviteReject
14. Properties
15. hashCode
16. index
17. runtimeType
18. Methods
19. noSuchMethod
20. toString
21. Operators
22. operator ==
23. Constants
24. values