code: private static Mirror getMirror(FeatureProvider provider, Collision collision)
      {
          if (collision.hasMirror() && provider.hasFeature(Mirrorable.class))
          {
              return provider.getFeature(Mirrorable.class).getMirror();
          }
          return Mirror.NONE;
      }
docs: Get the collision mirror.
  
  @param provider The provider owner.
  @param collision The collision reference.
  @return The collision mirror, {@link Mirror#NONE} if undefined.