margin property Null safety

1. baguette
2. ConversationWidget
3. ConversationWidget
4. margin property

ConversationWidget class

1. Constructors
2. ConversationWidget
3. Properties
4. conversation
5. hashCode
6. key
7. margin
8. onActions
9. onPress
10. padding
11. runtimeType
12. Methods
13. createElement
14. createState
15. debugDescribeChildren
16. debugFillProperties
17. noSuchMethod
18. toDiagnosticsNode
19. toString
20. toStringDeep
21. toStringShallow
22. toStringShort
23. Operators
24. operator ==