anchor.diff:      _completeCreation();
     }
   
  -  final Point worldAnchor;
  +  final Point _worldAnchor;
     final double lowerAngle;
     final double upperAngle;
     final bool enableLimit;
  
positive.code:   box2d.Joint _createB2Joint(PhysicsNode physicsNode) {
      // Create Joint Definition
      Vector2 vecAnchor = new Vector2(
        worldAnchor.x / physicsNode.b2WorldToNodeConversionFactor,
        worldAnchor.y / physicsNode.b2WorldToNodeConversionFactor
      );
  
      box2d.RevoluteJointDef b2Def = new box2d.RevoluteJointDef();
  
negative.code:   PhysicsJointRevolute(
      PhysicsBody bodyA,
      PhysicsBody bodyB,
      this._worldAnchor, {
        this.lowerAngle: 0.0,
        this.upperAngle: 0.0,
        this.enableLimit: false,
  