NavigationBarAction constructor Null safety

1. baguette
2. NavigationBarAction
3. NavigationBarAction
4. NavigationBarAction constructor

NavigationBarAction class

1. Constructors
2. NavigationBarAction
3. Properties
4. hashCode
5. icon
6. label
7. runtimeType
8. Methods
9. noSuchMethod
10. toString
11. Operators
12. operator ==