Activation/passivation listeners are intentionally non-transactional - and thus should never attempt to perform cache writes.
In order to trigger the requisite activation/passivation listeners, activation/passivation events need to lookup the cache entries relevant to a given session via SessionFactory.findValue(..). However, if there are entries missing (e.g. a creation meta data entry w/out a access meta data entry), this method will attempt to purge the orphaned entries. This should never be done within the context of an activation/passivation event.