NERtcAudioEffectEventCallback constructor Null safety

1. nertc
2. nertc
3. NERtcAudioEffectEventCallback
4. NERtcAudioEffectEventCallback constructor

NERtcAudioEffectEventCallback class

1. Constructors
2. NERtcAudioEffectEventCallback
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. onAudioEffectFinished
9. toString
10. Operators
11. operator ==