I wonder why the TCCL is the EarClassLoader when the second defining of the entity class is done by the aggregate classloader (during the EntityManagerFactoryBuilderImpl.buildHibernateConfiguration)? I thought the TCCL would be the TcclSafeAggregatedClassLoader instance.

Could you verify that the TCCL is the EarClassLoader when EntityManagerFactoryBuilderImpl.buildHibernateConfiguration() is called? It might be helpful to have a textual description of the aggregate classloader (including parent classloader and referenced classloaders). Should be possible to gather this information from a debugger.