Guenther, thanks for your highly informative responses. I think it's safe to say this isn't really a Hibernate 'bug', but it's certainly a curiosity in internal behavior.

Going a bit further, the original reason I found this behavior is that we're passing off entities to some code that is using the javabeans Introspector. This isn't a problem when we get actual instances of the Child class back from HEM, but when we get javaassist proxies, the code appears to be attempting to Introspect the javaassist class. We may be able to code around this by rewriting the code doing the Introspection – in that case, invoking Child.class methods through reflection upon the javaassist proxy will still function correctly, right?

I'm a little fuzzy on the particulars when doing reflection on proxies...