Java Hibernate映射异常

Question

Exception in thread "main" java.lang.ExceptionInInitializerError,
Caused by: org.hibernate.AnnotationException: @OneToOne or @ManyToOne on com.OrderManagementMaven.bo.ShoppingcartItem.customer references an unknown entity: com.OrderManagementMaven.bo.Customer
    at org.hibernate.cfg.ToOneFkSecondPass.doSecondPass(ToOneFkSecondPass.java:100)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processEndOfQueue(InFlightMetadataCollectorImpl.java:1823)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processFkSecondPassesInOrder(InFlightMetadataCollectorImpl.java:1767)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1655)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:295)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:86)
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:479)
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:85)
    at com.OrderManagementMaven.HibernateUtil.<clinit>(HibernateUtil.java:15)

@Entity
@Table(name = "SHOPPINGCART_ITEM")  
public class ShoppingcartItem {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private long itemId;
    
    @ManyToOne
    @JoinColumn(name="PRODUCTID")
    private Product product;
    
    @ManyToOne
    @JoinColumn(name="CUSTOMERID")
    private Customer customer;
    
    private int ammount;
    //...
}

@Entity
@Table(name = "PRODUCTCATALOG")  
public class Product {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private long id;
    private double price;
    private String
    //...
}

@Entity  
@Table(name = "CUSTOMER")  
public class Customer{
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private long id;
    @Column(name="CUSTOMERFIRSTNAME")
    private String firstname;
    @Column(name="CUSTOMERLASTNAME")
    private String lastname;
    //...
}

我认为错误并不在注释中，因为我更改了几次注释，仍然得到了相同的异常。