It looks like the only short-term workaround would be for you to compile JOCL yourself (or to just plug a constant value in there for now, or use Java reflection to get around the restriction against calling private methods). But this is an easy fix, I should be able to knock it out this weekend. I might have to send you the new files directly though, it seems like our central build system is offline for some reason.
I can put in the fix, it should be straightforward. Probably the reason that getWorkGroupInfo() was private is because calling the underlying clGetWorkGroupInfo() function requires some argument marshaling that's a little ugly and error-prone. I'll look into making it public though, just for future-proofing.