NERtcConnectionStateChangeReason constructor Null safety

1. netease_roomkit
2. netease_roomkit
3. NERtcConnectionStateChangeReason
4. NERtcConnectionStateChangeReason constructor

NERtcConnectionStateChangeReason class

1. Constructors
2. NERtcConnectionStateChangeReason
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. channelClosed
13. joinChannel
14. joinChannelFailed
15. joinSucceed
16. leaveChannel
17. mediaConnectionDisconnected
18. rejoinSucceed
19. requestChannelFailed
20. serverKicked
21. signalDisconnected
22. timeout