OperationCancelError constructor Null safety

1. sendbird_sdk
2. error
3. OperationCancelError
4. OperationCancelError constructor

OperationCancelError class

1. Constructors
2. OperationCancelError
3. Properties
4. code
5. hashCode
6. message
7. runtimeType
8. stackTrace
9. Methods
10. byaction
11. noSuchMethod
12. toJson
13. toString
14. Operators
15. operator ==