anchor.diff:  import 'package:flame_forge2d/flame_forge2d.dart';
   import 'package:pinball/game/components/components.dart';
   
  +/// {@template wall}
  +///
  +/// A generic wall component, a static component that can
  +/// be used to create more complex structures.
  +///
  +/// {@endtemplate}
   class Wall extends BodyComponent {
     Wall({
       required this.start,
  
positive.code:         );
  }
  
  class BottomWallBallContactCallback extends ContactCallback<Ball, BottomWall> {
    @override
    void begin(Ball ball, BottomWall wall, Contact contact) {
  
negative.code:   }
  }
  
  /// {@template bottom_wall}
  ///
  /// An specifc [Wall] used to create bottom boundary of the
  /// game board
  ///
  /// {@endtemplate}
  class BottomWall extends Wall {
    BottomWall(Forge2DGame game)
        : super(
  