anchor.diff:    /// ambient [ProgressIndicatorThemeData.linearTrackColor] will be used.
     /// If that is null, then the ambient theme's [ColorScheme.background]
     /// will be used to draw the track.
  -  ///
  -  /// This property is ignored if used in an adaptive constructor inside an iOS
  -  /// environment.
     /// {@endtemplate}
     @override
     Color? get backgroundColor => super.backgroundColor;
  
positive.code:   /// This value indicates the purpose of the progress bar, and will be
    /// read out by screen readers to indicate the purpose of this progress
    /// indicator.
    ///
    /// This property is ignored if used in an adaptive constructor inside an iOS
    /// environment.
    /// {@endtemplate}
    final String? semanticsLabel;
  
  
negative.code:   /// If null, the progress indicator is rendered with [color]. If that is null,
    /// then it will use the ambient [ProgressIndicatorThemeData.color]. If that
    /// is also null then it defaults to the current theme's [ColorScheme.primary].
    final Animation<Color?>? valueColor;
  
    /// {@template flutter.progress_indicator.ProgressIndicator.semanticsLabel}
  