padding property Null safety
Padding for the contents of the navigation bar.
If null, the navigation bar will adopt the following defaults:
- Vertically, contents will be sized to the same height as the navigation bar itself minus the status bar.
- Horizontally, padding will be 16 pixels according to iOS specifications unless the leading widget is an automatically inserted back button, in which case the padding will be 0.
Vertical padding won't change the height of the nav bar.
final EdgeInsetsDirectional? padding;