onCopy property Null safety

1. baguette
2. ConversationScreenWidget
3. ConversationScreenWidget
4. onCopy property

ConversationScreenWidget class

1. Constructors
2. ConversationScreenWidget
3. Properties
4. conversation
5. data
6. hashCode
7. itemMargin
8. itemPadding
9. key
10. listMargin
11. listPadding
12. onCopy
13. onFetch
14. onPress
15. onReport
16. onWrite
17. runtimeType
18. writerMargin
19. writerPadding
20. Methods
21. createElement
22. createState
23. debugDescribeChildren
24. debugFillProperties
25. getName
26. noSuchMethod
27. toDiagnosticsNode
28. toString
29. toStringDeep
30. toStringShallow
31. toStringShort
32. Operators
33. operator ==