Auto generate record ID class if no explicit @IdClass

Implemented by , but we still need to add a note to the documentation because otherwise nobody will know this exists!

Now I’ve added one idea for solution on Hibernate Core side

Of course, that is “TODO” in PR

But a core change would be necessary, no, because there’s no @IdClass annotation, so Hibernate needs to know where to find it.

I’ve created quick solution on Hibernate Processor side in pull request #9220

It is working, and I’ve tried to change as less as possible, but I do not claim that this is best solution.

Additionally, I did not changed anything on Hibernate Core side.