There are some valid arguments against using Optional as a method parameter type, but they are not good enough to say that you should avoid it at all costs
S. Shum. Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007), Volume 4604 von Lecture Notes in Artificial Intelligence, Seite 29-44. Berlin, Heidelberg, Springer-Verlag, (Juli 2007)