RefreshIndicatorState constructor Null safety

1. Flutter
2. material
3. RefreshIndicatorState
4. RefreshIndicatorState constructor

RefreshIndicatorState class

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