@Entity
public class Event {
     @Id
     private Long id;
     @ManyToOne
     private Device device;
     @Column
     private Impact impact;
     @Column
     private Severity severity;

    // THE PROBLEM
    @ManyToOne
    @JoinColumns({
        @JoinColumn(updatable = false, insertable = false,
            table = TableName.DEVICE, referencedColumnName = Device.PROPERTY_IMPACT_NATIVE_QUERY),
        @JoinColumn(updatable = false, insertable = false,
            table = TableName.DEVICE, referencedColumnName = Device.PROPERTY_PRIORITY_MATRIX_NATIVE_QUERY),
        @JoinColumn(updatable = false, insertable = false, referencedColumnName = "severity"),
        }
    )
    private Priority priority;
     ... getters/setters/other attrs ...
}

@Entity
public class Device {
     @Column
     private Impact impact;
     @ManyToOne
     private PriorityMatrix priorityMatrix;
     ... getters/setters/other attrs ...
}

@Entity
public class Priority {
     @EmbeddedId
     private PriorityId id;
     @Column
     private Long value;   
     ... getters/setters ...
}

@Embeddable
public class PriorityId {
     @Column
     private Severity severity;
     @Column
     private Impact impact;
     @ManyToOne
     private PriorityMatrix matrix;
     ... getters/setters ...
}

String EVENT_PRIORITY_QUERY =
        "SELECT event.*, priority.* \n"
        + "FROM   event \n"
        + "       INNER JOIN device \n"
        + "         ON ( event.device_id = device.id ) \n"
        + "       INNER JOIN trap_value \n"
        + "         ON ( event.event_trap_oid = trap_value.oid \n"
        + "              AND event.event_trap_value = trap_value.value ) \n"
        + "       INNER JOIN priority "
        + "         ON ( priority.prioritymatrix_id = device.prioritymatrix_id \n"
        + "              AND priority.impact = device.impact \n"
        + "              AND priority.severity = trap_value.severity ) \n"
        + "WHERE event.id = :eventId \n";

public Event read(Long eventId) {
        SQLQuery query = getEventQuery();

        query.setLong("eventId", eventId.longValue()); //$NON-NLS-1$       
        return extractEvent(query);
}

private Event getEventQuery() {
        SQLQuery query = createSQLQuery(EVENT_PRIORITY_QUERY);
        query.addEntity(Event.class);
        query.addEntity(Priority.class);
       
        return query;
}

private Event extractEvent(query) {
        Object[] eventAndPriorityResult = (Object[]) query.uniqueResult();
       
        if (eventAndPriorityResult != null) {
            Event evt = (Event) eventAndPriorityResult[0];
            Priority priority = (Priority) eventAndPriorityResult[1];
            evt.setPriority(priority);
            return evt;
        }
        return null;
}