PopupMenuButtonState<T> constructor Null safety

1. Flutter
2. material
3. PopupMenuButtonState<T>
4. PopupMenuButtonState constructor

PopupMenuButtonState class

1. Constructors
2. PopupMenuButtonState
3. Properties
4. context
5. hashCode
6. mounted
7. runtimeType
8. widget
9. Methods
10. activate
11. build
12. deactivate
13. debugFillProperties
14. didChangeDependencies
15. didUpdateWidget
16. dispose
17. initState
18. noSuchMethod
19. reassemble
20. setState
21. showButtonMenu
22. toDiagnosticsNode
23. toString
24. toStringShort
25. Operators
26. operator ==