code: public void registerCallback(C callback, CallbackOption<P> option)
  	{
  		callbacks.add(Pair.of(callback, option));
  		callbacks = Ordering.natural()
  							.reverse()
  							.onResultOf(Priority::ordinal)
  							.onResultOf(CallbackOption<P>::getPriority)
  							.onResultOf(Pair<C, CallbackOption<P>>::getRight)
  							.sortedCopy(callbacks);
  	}
docs: Registers a {@link ICallback} to be call when the {@link ICallbackPredicate} returns true.
  
  @param callback the callback
  @param option the option