code: public static <P extends ICallbackPredicate> CallbackOption<P> of(P predicate)
  		{
  			return new CallbackOption<>(checkNotNull(predicate), Priority.NORMAL);
  		}
docs: Constructs an empty {@link ICallback.CallbackOption}, with {@link Priority#NORMAL} priority and the specified
  {@link ICallbackPredicate}.
  
  @param <P> the generic type
  @param predicate the predicate
  @return the callback option