anchor.diff:    /// For determinate progress indicators, this will be defaulted to
     /// [ProgressIndicator.value] expressed as a percentage, i.e. `0.1` will
     /// become '10%'.
  -  ///
  -  /// This property is ignored if used in an adaptive constructor inside an iOS
  -  /// environment.
     /// {@endtemplate}
     final String? semanticsValue;
   
  
positive.code:   /// [ProgressIndicatorThemeData.color] will be used. If that
    /// is null then the current theme's [ColorScheme.primary] will
    /// be used by default.
    ///
    /// This property is ignored if used in an adaptive constructor inside an iOS
    /// environment.
    /// {@endtemplate}
    final Color? color;
  
  
negative.code:   /// ambient [ProgressIndicatorThemeData.linearTrackColor] will be used.
    /// If that is null, then the ambient theme's [ColorScheme.background]
    /// will be used to draw the track.
    /// {@endtemplate}
    @override
    Color? get backgroundColor => super.backgroundColor;
  