I can confirm this problem. I got the same error message on Mac OS Snow Leopard with Eclipse 3.5 SR1. Interestingly, the latest version here on sourceforge download page, version 1.5.15, works fine. So why do we get version 1.5.16 from eclipse update site in the first place? That version doesn't even exist here...
2009-10-02 17:44:21 UTC in JavaCC Eclipse Plugin
