public void createData() {
OpenJPAEntityManager em = emf.createEntityManager();
em.getTransaction().begin();
FetchA a1 = new FetchA();
a1.setText("a1");
FetchB b1 = new FetchB();
b1.setText("b1");
a1.setB(b1);
em.persist(a1);
em.persist(b1);
em.getTransaction().commit();
}