Action<T extends Intent> constructor Null safety

1. Flutter
2. widgets
3. Action<T extends Intent>
4. Action constructor

Action class

1. Constructors
2. Action
3. overridable
4. Properties
5. callingAction
6. hashCode
7. intentType
8. isActionEnabled
9. runtimeType
10. Methods
11. addActionListener
12. consumesKey
13. debugFillProperties
14. invoke
15. isEnabled
16. noSuchMethod
17. notifyActionListeners
18. removeActionListener
19. toDiagnosticsNode
20. toString
21. toStringShort
22. Operators
23. operator ==