anchor.diff:    ///
     /// The [indicatorPadding] parameter defaults to [EdgeInsets.zero], and must not be null.
     ///
  -  /// If [indicator] is not null, then [indicatorWeight], [indicatorPadding], and
  -  /// [indicatorColor] are ignored.
  +  /// If [indicator] is not null or provided from [TabBarTheme],
  +  /// then [indicatorWeight], [indicatorPadding], and [indicatorColor] are ignored.
     const TabBar({
       Key key,
       @required this.tabs,
  
positive.code:   /// If this parameter is null, then the value of the Theme's indicatorColor
    /// property is used.
    ///
    /// If [indicator] is specified, this property is ignored.
    final Color indicatorColor;
  
    /// The thickness of the line that appears below the selected tab.
  
negative.code:   ///
    /// The default value of [indicatorPadding] is [EdgeInsets.zero].
    ///
    /// If [indicator] is specified or provided from [TabBarTheme],
    /// this property is ignored.
    final EdgeInsetsGeometry indicatorPadding;
  
    /// Defines the appearance of the selected tab indicator.
    ///
    /// If [indicator] is specified or provided from [TabBarTheme],
    /// the [indicatorColor], [indicatorWeight], and [indicatorPadding]
    /// properties are ignored.
    ///
    /// The default, underline-style, selected tab indicator can be defined with
    /// [UnderlineTabIndicator].
  