Expose Metamodel getters in the SessionFactory APIS

[DavideD]

From this conversation on Zulip:

you might want to look into exposing all metamodels directly in Reactive though. From what I can see only the JPA one is exposed right now, but not org.hibernate.metamodel.MappingMetamodel, which needs to be retrieved through hoops (see above)

[gavinking]

Not sure what this issue is about, but if it's about exposing org.hibernate.metamodel.MappingMetamodel on an API, we should definitely not do that. MappingMetamodel exposes SPI-level types. Notice that SessionFactory in ORM does not expose this type.

[DavideD]

Ok, something to look into

[gavinking]

Note that it's already exposed via ReactiveSession.getFactory().getMappingMetamodel(). (Which is an SPI.)