Do want to be careful about avoiding "method explosion" due to overloading... Overloading here would simply be addition of 4 methods on HibernateEntityManagerFactory to shadow the 4 on EntityManagerFactory. But if we start exposing more creational methods through HibernateEntityManagerFactory this can easily start to explode (see the mess we used to have with all the overloaded forms of #openSession on SessionFactory for an example).

Do we go with a builder right off the bat here to avoid that?