SelectionChangedCause constructor Null safety

1. Flutter
2. services
3. SelectionChangedCause
4. SelectionChangedCause const constructor

SelectionChangedCause enum

1. Constructors
2. SelectionChangedCause
3. Values
4. tap
5. doubleTap
6. longPress
7. forcePress
8. keyboard
9. toolbar
10. drag
11. scribble
12. Properties
13. hashCode
14. index
15. runtimeType
16. Methods
17. noSuchMethod
18. toString
19. Operators
20. operator ==
21. Constants
22. values