backgroundColor property Null safety
final
The fill color to use for an app bar's Material.
If null, then the AppBarTheme.backgroundColor is used. If that value is also null, then AppBar uses the overall theme's ColorScheme.primary if the overall theme's brightness is Brightness.light, and ColorScheme.surface if the overall theme's brightness is Brightness.dark.
If this color is a MaterialStateColor it will be resolved against MaterialState.scrolledUnder when the content of the app's primary scrollable overlaps the app bar.
This property is used to configure an AppBar.
Implementation
final Color? backgroundColor;