Your test case starts failing from 4.1.10.Final through all of 4.2.x (which coincides with a few Javassist upgrades). But with 4.3.0.Beta5 (released today), it works. 4.2.x's dependency on Javassist was...volatile. There were numerous issues and regressions that came up in Javassist 3.16 through 3.17 that caused issues for much of JBoss. ORM 4.3 is now on Javassist 3.18.1. Plus, we now have an internal engineer directly committing on Javassist. For now, I'm calling this one "Cannot Reproduce", but if it comes up again past 4.3.0, please let us know!