StreamSinkCompleter<T> constructor Null safety

1. Flutter
2. async
3. StreamSinkCompleter<T>
4. StreamSinkCompleter constructor

StreamSinkCompleter class

1. Constructors
2. StreamSinkCompleter
3. Properties
4. hashCode
5. runtimeType
6. sink
7. Methods
8. noSuchMethod
9. setDestinationSink
10. setError
11. toString
12. Operators
13. operator ==
14. Static methods
15. fromFuture