public void unidirectionalOneToOne() throws Exception {
Vehicle vehicle = new Vehicle();
vehicle.setBrand("Mercedes");
Wheel wheel = new Wheel();
wheel.setVehicle(vehicle);
em.persist(vehicle);
em.persist(wheel);
em.flush();
em.clear();
log.debug("Wheel=[{}]", wheel);
wheel = em.find(Wheel.class, wheel.getId());
assertThat(wheel).isNotNull();
vehicle = wheel.getVehicle();
assertThat(vehicle).isNotNull();
em.remove(wheel);
em.remove(vehicle);
em.flush();