Hibernate version: 2.1

Using latest version of Xdoclet, How do I write the xdoclet code to generate hibernate mapping documents for a "many-to-many" relation between UE table and TRAFFIC with an additional column.

UE (UE_ID, ...)
TRAFFIC(TRAFFIC_ID, ...)
UE_TRAFFIC(UE_ID, TRAFFIC_ID, IS_UE_ORIGINATING)

I've created a UeTrafficBean but are a bit unsure of how to set the primary key here...

In TrafficBean I've got the code:
/**
* @hibernate.set table="UE_PROPERTY_TRAFFIC"
* @hibernate.collection-key column="STATISTICS_ID"
* @hibernate.collection-composite-element class="UeLinkedTrafficBean"
* @return Returns the traffic.
*/
public Set<TrafficBean> getTraffic() {
return traffic;
}

I have no relation to traffic in UeBean.