In truth, I am not all that familiar with the Hibernate class that you are using.
Still, if you are sure it is working correctly and double checked everything, then "if it works, it works"
But I am still not clear why you are
DomainObject entity = (DomainObject) event.getSession().getPersistenceContext().getEntity(
Maybe I am missing something
DomainObject entity = (DomainObject) event.getEntity();