private void addEmailToPerson(Long personId, String emailAddress) {

        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        session.beginTransaction();

        Person aPerson = (Person) session.load(Person.class, personId);

        // The getEmailAddresses() might trigger a lazy load of the collection
        aPerson.getEmailAddresses().add(emailAddress);

        session.getTransaction().commit();
}

private void addEmailToPerson(Long personId, String emailAddress) {

        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        session.beginTransaction();
        Person aPerson = (Person) session.createQuery("from Person p left join fetch p.emailAddresses where p.id = :pid").setParameter("pid", personId).uniqueResult(); // Eager fetch the collection so we can use it detached
        session.getTransaction().commit();
       
       aPerson.getEmailAddresses().add(emailAddress); // aPerson (and its collection) is detached
       
       Session session2 = HibernateUtil.getSessionFactory().getCurrentSession();
       session2.beginTransaction();
       session2.update(aPerson); // Reattachment of aPerson
       session2.getTransaction().commit();
    }