Sorry. I somehow missed this reply.

Nothing new,

True. But old is not a pseudonym for "bad"; much less new a pseudonym for "good".

I already listed this possibility

Yes, you did. But I wonder why you dismiss it so readily?

and BTW wasn't even talking about autobox.

Did you miss the "either objects or" part of my post you quoted?

And was I dreaming when I thought I read: "Another approach would be to use something like autobox" in the OP?

Y'know, I'd really like to qet a squint at whatever piece of code it is, that you've had trouble either refactoring or porting, that prompted your current obsession, investigations :)