我得到了以下异常
第一个月
即使一切似乎Map正确，当我调试的值，应该是空的是存在的。
下面是给出该异常的代码和测试示例：

@Entity
@Table(name = "ITEM")
@Setter
public class ItemEntity {
    
    //...
    private CartEntity cart;

    public ItemEntity() {}
    
    // getters and setters
    @ManyToOne(optional = false, fetch = FetchType.LAZY)
    @JoinColumn(name = "cart_id", nullable = false, insertable = false, updatable = false)
    public CartEntity getCart()
    {
        return cart;
    }
}


@Entity
@Table(name="CART")
@Setter
public class CartEntity {

    //...
    private List<ItemEntity> items;

    // getters and setters
    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "cart")
    @OrderColumn(name = "RANK")
    public List<ItemEntity> getItems()
    {
        return items;
    }
}

@Repository
public interface ItemEntityRepository
    extends JpaRepository<ItemEntity, Long>
{
}

这里的测试仍然给予空值，即使在调试值时也是如此

@Execution(ExecutionMode.CONCURRENT)
@DataJpaTest(showSql = false)
class ItemEntityRepositoryTest
{
    @Autowired
    private TestEntityManager entityManager;

    @Autowired
    private ItemEntityRepository repository;
    
    private Long entityId;
        
    @BeforeEach
    void init()
    {
        Item item = new Item();
        // ... fill other item attributes here
    
        CartEntity cart = new CartEntity();
        // ... fill other cart attribute here

        Long idSet = (Long) entityManager.persistAndGetId(cart);
        cart.setId(idSet);
        cart.setItems(Collections.singletonList(item));

        item.setCompetitionConfigurationSet(cart);

        entityId = (Long) entityManager.persistAndGetId(item);
    }

    @Test
    void findAll_existingItems_returnsAllItems()
    {
        List<Items> items = repository.findAll();
        assertEquals(1, items.size());
    }
}

注意，获取单个实体的测试工作正常。