public void setPropertyValue(Object id, Object value) {
   if (id == idOppositeShown)
     getReference().setOppositeShown(BooleanPropertyDescriptor.toModel(value));
   else super.setPropertyValue(id, value);
 }
 public Object getPropertyValue(Object id) {
   if (id == idOppositeShown)
     return BooleanPropertyDescriptor.fromModel(getReference().isOppositeShown());
   return super.getPropertyValue(id);
 }