Hibernate 異常：“@OneToOne or @ManyToOne on XXX references an unknown entity: XXX”

使用Hibernate進行自關聯時@ManyToOne 定義的類型Order是接口，需要顯示指定實現類

@ManyToOne(fetch=FetchType.LAZY, targetEntity = OrderImpl.class, cascade = CascadeType.MERGE)  
@JoinColumn(name="PARENT_ORDER_ID")  
private Order parent;