NERtcAudioDeviceState constructor Null safety

1. netease_roomkit
2. netease_roomkit
3. NERtcAudioDeviceState
4. NERtcAudioDeviceState constructor

NERtcAudioDeviceState class

1. Constructors
2. NERtcAudioDeviceState
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. closed
13. initializationError
14. initialized
15. opened
16. startError
17. unInitialized
18. unknownError