@Test
public void testReferences() {

    Grandfather g = new Grandfather();
    Parent p1 = new Parent("p1");
    Child c1 = new Child("c1");
    p1.setProp6(c1);
    admin.createObjects(Arrays.asList(c1, p1));
    Optional<Parent> p = admin.get(Parent.class, "p1");
    System.out.println(p.get().getProp6());
}