hibernate - OneToOne 更新後の NullPointerException

Question

私はHibernateが初めてで、このイライラする問題に取り組んでいます。と の 2 つのクラスがLocationありAddressます。Addressはエンティティであり、Location主キーへの外部キーがあります。だからここにあるLocation

public class Location implements Serializable {
//Rest of code omitted
@OneToOne(mappedBy = "location", cascade = CascadeType.ALL)
    public Address getAddress() {
        return address;
    }
}  

とAddress

public class Address implements Serializable {
    //Rest of code ommitted
    @OneToOne
    @JoinColumn(name = "LOCATION_FK")
    public Location getLocation() {
        return location;
    }
}

ロケーションオブジェクトのアドレスを更新しようとしていますが、起こっていないようです。

public void updateAddress(Location location, Address address) {
    Session session = HibernateUtil.getSessionFactory().openSession();
    Transaction tx = session.beginTransaction();

    tx.begin();
    Location persistedLocation = (Location) session.get(Location.class, location.getId());
    Address persistedAddress = persistedLocation.getAddress();
    session.delete(persistedAddress);
    persistedLocation.setAddress(address);
    tx.commit();

    session.close();
}

これが私の単体テストです

//Setting variables 
Location location = new Location(); 
Address address = new Address("123456", "TOWN", "CITY", 12345); 
LocationDAO instance = new LocationDAO();

//Add the first location
boolean result = instance.addLocation(location, address);
assertTrue(result); 

//Get it back from database
Location persistedLocation = instance.getLocations().get(0); 
assertEquals(location.getAddress().getAddressLine(), persistedLocation.getAddress().getAddressLine());

Address newAddress = new Address("987654321", "Chicago", "IL", 11234); 

instance.updateAddress(persistedLocation, newAddress);
persistedLocation = instance.getRentalLocations().get(0); 

//Fails on the line below
//assertEquals(newAddress.getAddressLine(), persistedLocation.getAddress().getAddressLine()); 

私は何を間違っていますか？ありがとうございました