anchor.diff:          backgroundImage: backgroundImage != null ? new BackgroundImage(
             image: backgroundImage
           ) : null,
  -        shape: BoxShape.circle
  +        shape: BoxShape.circle,
         ),
  -      child: new Center(
  +      child: child != null ? new Center(
           child: new DefaultTextStyle(
             style: theme.primaryTextTheme.title,
  -          child: child
  +          child: child,
           )
  -      )
  +      ) : null,
       );
     }
   }
  
positive.code: 
    /// The background image of the circle. Changing the background
    /// image will cause the avatar to animate to the new image.
    final ImageProvider backgroundImage;
  
    /// The size of the avatar. Changing the radius will cause the
    /// avatar to animate to the new size.
    final double radius;
  
    @override
    Widget build(BuildContext context) {
      final ThemeData theme = Theme.of(context);
      final Color color = backgroundColor ?? theme.primaryColor;
  
      return new AnimatedContainer(
        width: radius * 2.0,
        height: radius * 2.0,
  
negative.code:   }) : super(key: key);
  
    /// The widget below this widget in the tree.
    ///
    /// Typically a [Text] widget. If the [CircleAvatar] is to have an image, use
    /// [backgroundImage] instead.
    final Widget child;
  
    /// The color with which to fill the circle. Changing the background
  