NERtcConnectionState constructor Null safety

1. netease_roomkit
2. netease_roomkit
3. NERtcConnectionState
4. NERtcConnectionState constructor

NERtcConnectionState class

1. Constructors
2. NERtcConnectionState
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. connected
13. connecting
14. disconnected
15. failed
16. reconnecting
17. unknown