Java SpringDataJPA与H2数据库：连接不同项目中的两个实体

我有两个带有两个实体（客户和购物车）的Eclipse项目

项目客户服务：

    @Entity
    public class Customer {

        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private int customerId;

        private String name;
        private String address;

        @OneToOne
        @JoinColumn(name = "cart_test")
        private Cart cart;

        public Customer(Cart cart) {
           this.cart = cart;

@Entity
public class Cart {

    @Id
    @JoinColumn(name = "cart_id")
    private int cartId;

    private Map<Integer, CartItem> cartItems;
    private int numberOfArticles;

    public Cart() {
        cartItems = new HashMap<Integer, CartItem>();
        numberOfArticles = 0;
    }

项目微服务：

    @Entity
    public class Customer {

        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private int customerId;

        private String name;
        private String address;

        @OneToOne
        @JoinColumn(name = "cart_test")
        private Cart cart;

        public Customer(Cart cart) {
           this.cart = cart;

@Entity
public class Cart {

    @Id
    @JoinColumn(name = "cart_id")
    private int cartId;

    private Map<Integer, CartItem> cartItems;
    private int numberOfArticles;

    public Cart() {
        cartItems = new HashMap<Integer, CartItem>();
        numberOfArticles = 0;
    }

如何连接这两个实体？我希望我的数据库中有这样的内容：

<item>
  <customerId>1000</customerId>
  <name>name</name>
  <address>email@email.com</address>
  <cart_test>Cart</cart_test>
  <!-- OR something like -->
  <cart_id>CartId</cart_id>

---

你不能这样做。Hibernate希望映射使用过的模型。在其他项目中映射它不会给外部世界带来任何错误，因为它可以以任何方式密封

解决方法是在一些模块中定义模型，这些模块将由项目共享