Envers doesn't support HBM 'properties' element?

[code6226]

Envers doesn't seem to support grouping relations inside of an <properties> element. In my case, I'm trying to use the unique attribute of the properties tag as described here. Is there an alternative way to achieve the same behavior that is supported?

Works:

<joined-subclass name="Tcr2IeAssociation" table="TCR_IE">
  <key column="ID_BB" />

  <many-to-one name="technicalComponentRelease" column="ID_TCR" not-null="true"/>
  <many-to-one name="infrastructureElement" column="ID_IE" not-null="true"/>

</joined-subclass>

Does not work:

<joined-subclass name="Tcr2IeAssociation" table="TCR_IE">
  <key column="ID_BB" />
  <properties name="uniqueEnds" unique="true">
    <many-to-one name="technicalComponentRelease" column="ID_TCR" not-null="true"/>
    <many-to-one name="infrastructureElement" column="ID_IE" not-null="true"/>
  </properties>      
</joined-subclass>

Removing the unique attribute has no effect.
The same error is thrown whenever the properties tag is in use:

Unable to read the mapped by attribute for infrastructureElementAssociations in MY.model.Tcr2IeAssociation!

     [java]     at org.hibernate.envers.configuration.metadata.CollectionMetadataGenerator.getMappedBy(CollectionMetadataGenerator.java:561)
     [java]     at org.hibernate.envers.configuration.metadata.CollectionMetadataGenerator.addOneToManyAttached(CollectionMetadataGenerator.java:161)
     [java]     at org.hibernate.envers.configuration.metadata.CollectionMetadataGenerator.addCollection(CollectionMetadataGenerator.java:144)
     [java]     at org.hibernate.envers.configuration.metadata.AuditMetadataGenerator.addValue(AuditMetadataGenerator.java:167)
     [java]     at org.hibernate.envers.configuration.metadata.AuditMetadataGenerator.addProperties(AuditMetadataGenerator.java:187)
     [java]     at org.hibernate.envers.configuration.metadata.AuditMetadataGenerator.generateSecondPass(AuditMetadataGenerator.java:447)
     [java]     at org.hibernate.envers.configuration.EntitiesConfigurator.configure(EntitiesConfigurator.java:113)
     [java]     at org.hibernate.envers.configuration.AuditConfiguration.<init>(AuditConfiguration.java:86)
     [java]     at org.hibernate.envers.configuration.AuditConfiguration.getFor(AuditConfiguration.java:99)
     [java]     at org.hibernate.envers.event.AuditEventListener.initialize(AuditEventListener.java:335)
     [java]     at org.hibernate.event.EventListeners$1.processListener(EventListeners.java:198)
     [java]     at org.hibernate.event.EventListeners.processListeners(EventListeners.java:181)
     [java]     at org.hibernate.event.EventListeners.initializeListeners(EventListeners.java:194)