brightness property
The brightness of the app bar's material. Typically this is set along with backgroundColor, iconTheme, textTheme.
If this property is null, then ThemeData.appBarTheme.brightness is used,
if that is also null, then the appBarTheme can be used to configure the
appearance of AppBars. The appearance of Keyboards for TextFields now uses
the overall theme's ThemeData.brightness and can also be customized with
TextField.keyboardAppearance. The brightness of any color can be found with
ThemeData.estimateBrightnessForColor.
Implementation
final Brightness? brightness;