EventSink<T> constructor Null safety

1. Dart
2. dart:async
3. EventSink<T>
4. EventSink constructor

EventSink class

1. Constructors
2. EventSink
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. add
8. addError
9. close
10. noSuchMethod
11. toString
12. Operators
13. operator ==