Envers domain model uses Hibernate's MAP "entity mode" which is outside the scope of JPA. Furthermore MAP mode is considered a de-typed mode since it is always a Map.

So I do not agree with must not here.

IMO, if returning null is not appropriate for a user we should cover this under org.hibernate.metamodel.internal.JpaMetaModelPopulationSetting#IGNORE_UNSUPPORTED. Chris Cranford maybe we even want to make this automatic? I am a little worried though about blanket ignoring all MAP mode entities. Probably this is more along the lines we have discussed before where it would be nice to know which entities come from Envers (and I told you Search has a similar use case).