JavaCC: How can I make generated boilerplate classes package-private?

Question

Hello, everyone!

I know that I can specify the option SUPPORT_CLASS_VISIBILITY_PUBLIC = false; inside a .jj file. But this makes only the generated class itself package-private.

The "boilerplate" classes (such as ParseException) are still public. This is very annoying, since I use java.text.ParseException for public exposure of the API.

Any ideas how to make the boilerplate classes also package-private?