private void removeObjectsExercise() {
        List<Town> towns = this.entityManager
                .createQuery("SELECT t FROM Town AS t " +
                        "WHERE length(t.name) > 5", Town.class)
                .getResultList();


        this.entityManager.getTransaction().begin();

        towns
                .forEach(this.entityManager::detach);
        this.entityManager.flush();
        this.entityManager.getTransaction().commit();

        entityManager.getTransaction().begin();
        entityManager.createQuery("UPDATE Town t SET t.name = lower(t.name) " +
                "WHERE length(t.name) <= 5 ").executeUpdate();
        entityManager.getTransaction().commit();
        entityManager.close();
    }