[hibernate-dev] Try and sneak HHH-6724 in Core 4.0

[Emmanuel Bernard]

I've tracked and hunted down a small but impacting bug for Hibernate OGM.
https://hibernate.onjira.com/browse/HHH-6724

I am not sure about the CR status but if you could squeeze this one in, I would be grateful. I have committed it in upstream master and all tests pass.

BTW this bug was also present in the (future) metadata source part of the code (in some form). Inheritance could not have worked before the fix. I'm not sure it works now but that's one step closer :)

Emmanuel