SdkAccessor constructor Null safety

1. sendbird_sdk
2. sendbird_sdk_accessor
3. SdkAccessor
4. SdkAccessor constructor

SdkAccessor class

1. Constructors
2. SdkAccessor
3. Properties
4. appState
5. cmdManager
6. eventManager
7. hashCode
8. runtimeType
9. sdk
10. webSocket
11. Methods
12. noSuchMethod
13. toString
14. Operators
15. operator ==