'interleaving' prop on connection factories and datasources is always null, even when underlying ds.xml file contains the interleaving element

My ds.xml file:

<connection-factories>
<tx-connection-factory>
<jndi-name>MyXATxCF</jndi-name>
<rar-name>jms-ra.rar</rar-name>
<connection-definition>org.jboss.resource.adapter.jms.JmsConnectionFactory</connection-definition>
...
<interleaving/>
</tx-connection-factory>
</connection-factories>

But the interleaving ManagedProperty on this CF is still null, rather than true:

name=interleaving, viewUse=NONE, readOnly=false, mandatory=false, removed=false, type=SimpleMetaType:java.lang.Boolean, value= <<<null>>>