如何在spring boot中使用嵌套循环导航未知嵌套对象

@Entity
public class User {
    @Id
    private Long id;
    private String name;
    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    private List<Order> orders;
    // getters and setters
}

@Entity
public class Order {
    @Id
    private Long id;
    private String orderNumber;
    @ManyToOne
    @JoinColumn(name = "user_id")
    private User user;
    @OneToMany(mappedBy = "order", cascade = CascadeType.ALL)
    private List<Item> items;
    // getters and setters
}

@Entity
public class Item {
    @Id
    private Long id;
    private String name;
    @ManyToOne
    @JoinColumn(name = "order_id")
    private Order order;
    // getters and setters
}

public interface UserRepository extends JpaRepository<User, Long> {
}

public interface OrderRepository extends JpaRepository<Order, Long> {
}

public interface ItemRepository extends JpaRepository<Item, Long> {
}

@RestController
@RequestMapping("/users")
public class UserController {
    @Autowired
    private UserRepository userRepository;

    @GetMapping
    public List<User> getUsers() {
        return userRepository.findAll();
    }
}

@Entity
public class User {
    // ...
    @JsonManagedReference
    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    private List<Order> orders;
    // ...
}

@Entity
public class Order {
    // ...
    @JsonBackReference
    @ManyToOne
    @JoinColumn(name = "user_id")
    private User user;
    // ...
}