hibernate hbm.xml editor wierd error

[mdiskin]

I get this error:
ERROR 41:29 Attribute "order-by" must be declared for element type "many-to-many"

but only on the visual/tree view. The source view is fine and says the xml is valid.

Here's the config that's causing the error (which came from jboss support, but only the dev studio is supported, not the hibernate tools version and dev studio cannot be installed into my STS ide).

<map name="billers" inverse="true" schema="INVADMIN"
 table="BILLER_GROUP_ASSIGNMENT" mutable="true" sort="unsorted"
 optimistic-lock="true" embed-xml="true" >
 <key column="BILLER_GROUP_ID" on-delete="noaction" />
 <map-key type="long" formula="BILLER_ID" />
 <many-to-many column="BILLER_ID" unique="false" order-by="BILLER_NM"
 class="com.arccorp.database.invoicing.domain.Biller" embed-xml="true"
 not-found="exception" />
 </map>

[akazakov]

Which version of JBoss Tools do you use? Hibernate?
I can't reproduce it for JBoss Tools 3.0.0GA/Hibernate 3 (http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd)