it looks like there might be an issue with building the mappedSuperclassByMappedSuperclassMapping map in MetadataContext.java
Everything was working like a champ in 4.3.10, I decided to upgrade to get JDK8 Date stuff.
In my code I have bunch of entities that extend by AbstractAppObject. and when AttributeFActory.getDeclarerEntityMetamodel is called for the first time I have my DiscussionMessage entity in the (MetadataContext) mappedSuperclassByMappedSuperclassMapping 3 times. this causes virtualIdentifierMemberResolver to find the wrong entity at some point. I end up with a "expecting IdClass mapping" IllegalArgumentException.
If remove my DiscussionMessage entity then I end up with the 'next' entity that has the same chain of abstract classes.
some of my code -
from spring -