Version: JBoss EJB-3RC8

I have a simple class hierarchy that uses joined inheritance:

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class MaterialMaster {
 private String externalId;
}

@Entity
@PrimaryKeyJoinColumn(name="ID")
public class SparePartMaster extends MaterialMaster {

}

This hierarchy is referenced by another class:

@Entity
public class RecallOrderLine {
 @ManyToOne(fetch=FetchType.LAZY, optional=false)
 private RecallOrder recallOrder;

 @OneToOne(fetch=FetchType.LAZY, optional=false)
 private MaterialMaster material;
}

When I query

SELECT r FROM RecallOrderLine r
WHERE r.recallOrder=:recallOrder
 AND r.material =:material

the returned RecallOrderLine has a SparePartMaster instance as expected.

Now when I query

SELECT r FROM RecallOrderLine r
WHERE r.recallOrder=:recallOrder
 AND r.material.externalId =:matExtKey

the returned RecallOrderLine has a MaterialMaster instance only!

My DB is correct. So it must be a bug in Hibernate.