NERtcVideoRendererEventListener constructor Null safety

1. netease_roomkit
2. netease_roomkit
3. NERtcVideoRendererEventListener
4. NERtcVideoRendererEventListener constructor

NERtcVideoRendererEventListener class

1. Constructors
2. NERtcVideoRendererEventListener
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. onFirstFrameRendered
9. onFrameResolutionChanged
10. toString
11. Operators
12. operator ==