JPA Lookup Hierarchy Mapping

Question

Given a lookup table:

  | ID | TYPE         | CODE    | DESCRIPTION          |
  | 1  | ORDER_STATUS | PENDING | PENDING DISPOSITION  |
  | 2  | ORDER_STATUS | OPEN    | AWAITING DISPOSITION |
  | 3  | OTHER_STATUS | OPEN    | USED BY OTHER ENTITY |

If I have an entity:

@MappedSuperclass @Table(name="LOOKUP")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="TYPE", discriminatorType=DiscriminatorType.STRING)
public abstract class Lookup {
   @Id @Column(name="ID") int id;
   @Column(name="TYPE") String type;
   @Column(name="CODE") String code;
   @Column(name="DESC") String description;
    ...
}

Then a subclass:

@Entity @DiscriminatorValue("ORDER_STATUS")
public class OrderStatus extends Lookup {
}

The expectation is to map it:

@Entity @Table(name="ORDERS")
public class OrderVO {
   ...
   @ManyToOne
   @JoinColumn(name="STATUS", referencedColumnName="CODE")
   OrderStatus status;
   ...
}

So that the CODE is stored in the database. I expected that if I wrote:

OrderVO o = entityManager.find(OrderVO.class, 123);

the SQL generated using OpenJPA would look something like:

SELECT t0.id, ..., t1.CODE, t1.TYPE, t1.DESC 
FROM ORDERS t0
LEFT OUTER JOIN LOOKUP t1 ON
  t0.STATUS = t1.CODE AND t1.TYPE = 'ORDER_STATUS' WHERE
t0.ID = ?

But the actual SQL that gets generated is missing the

AND t1.TYPE = 'ORDER_STATUS'

This causes a problem when the CODE is not unique. Is there a way to have the discriminator included on joins or am I doing something wrong here?