加载时JPA/Hibernate继承：IllegalArgumentException，尝试设置错误的子类

我使用的是JBoss 6.1，我遇到了JPA缠绕的情况，因此我得到了以下错误消息：

IllegalArgumentException:无法将设备B field EquipmentCycleB.equipment设置为设备A

假设每个实体都有一个@Id注释字段：

第一等级

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "DIS", discriminatorType = DiscriminatorType.STRING, length = 1)
public abstract class Equipment { ... }

@Entity
@DiscriminatorValue("A")
public class EquipmentA extends Equipment { ... }

@Entity
@DiscriminatorValue("B")
public class EquipmentB extends Equipment { ... }

第二等级

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "DIS", discriminatorType = DiscriminatorType.STRING, length = 10)
public abstract class EquipmentCycle { 

   ...

}

@Entity
@DiscriminatorValue("A")
public class EquipmentCycleA extends EquipmentCycle {

   @JoinColumn(name = "EQUIPMENT_ID", referencedColumnName = "ID")
   @ManyToOne
   private EquipmentA equipment;

   ...

}

@Entity
@DiscriminatorValue("B")
public class EquipmentCycleB extends EquipmentCycle { 

   @JoinColumn(name = "EQUIPMENT_ID", referencedColumnName = "ID")
   @ManyToOne
   private EquipmentB equipment;

   ...

}

到目前为止没什么奇怪的，继续吧，全班说状态

@Entity
public class State {

   @JoinColumn(name = "ENTITY_ID", referencedColumnName = "ID", nullable = false)
   @ManyToOne
   private EnityWithState enityWithState;

   @JoinColumn(name = "EQUIPMENT_ID", referencedColumnName = "ID")
   @ManyToOne
   private Equipment equipment;

   @JoinColumn(name = "EQUIPMENT_CYCLE_ID", referencedColumnName = "ID")
   @ManyToOne
   private EquipmentCycle equipmentCycle;

   ...

}

以及国家所属的阶级

public class EnityWithState { 

...

    @OneToMany(mappedBy = "enityWithState", fetch = FetchType.LAZY, cascade = CascadeType.ALL,   orphanRemoval = true)  
    private List<State> stateHistory;

    ...

}

最后，当我尝试加载id为1的EnityWithState时，我得到了以下错误：

IllegalArgumentException:无法将设备B field EquipmentCycleB.equipment设置为设备A

有人知道吗？我在谷歌上搜索了一下，但什么也没找到。 可能是Hibernate/JPA错误吗

提前谢谢你的帮助

Table Equipment

ID  DIS
--------------------------------
1   A  ...
2   B  ...

Table EquipmentCycle

ID  DIS  EQUIPMENT_ID
--------------------------------
 1   A    1
 2   B    2

Table State

ID  ENTITY_ID EQUIPMENT_ID EQUIPMENT_CYCLE_ID
---------------------------------------------
1     1           1              1
2     1           2              2