anchor.diff:  
   class CustomIcon extends StatelessWidget {
     const CustomIcon({
  -    @required this.kind,
  -    @required this.text,
  +    required this.kind,
  +    required this.text,
       this.isAbstract = false,
     });
   
  
positive.code: 
  class ThemedImageIcon extends StatelessWidget {
    const ThemedImageIcon({
      @required this.lightModeAsset,
      @required this.darkModeAsset,
    });
  
    final String lightModeAsset;
  
negative.code: /// An icon with one character
  class CircleIcon extends StatelessWidget {
    const CircleIcon({
      required this.text,
      required this.color,
    });
  
    /// Text to display. Should be one character.
  