label property Null safety

1. flutter_json_widgets
2. widget
3. Chip
4. label property

Chip class

1. Constructors
2. Chip
3. fromJson
4. Properties
5. autofocus
6. avatar
7. backgroundColor
8. clipBehavior
9. copyWith
10. deleteButtonTooltipMessage
11. deleteIcon
12. deleteIconColor
13. elevation
14. hashCode
15. key
16. label
17. labelPadding
18. labelStyle
19. materialTapTargetSize
20. onDeleted
21. padding
22. runtimeType
23. shadowColor
24. shape
25. side
26. surfaceTintColor
27. visualDensity
28. Methods
29. map
30. mapOrNull
31. maybeMap
32. maybeWhen
33. noSuchMethod
34. toJson
35. toString
36. when
37. whenOrNull
38. Operators
39. operator ==