Property substitution in remote-outbound-connection for username doesn't work

Issue

When we try to substitute a property for the username in the remote-outbound-connection configuration in the standalone.xml the property substitution doesn't work.

doesn't work:

<remote-outbound-connection name="remote-ejb-connection" outbound-socket-binding-ref="remote-ejb-1" username="${remote-ejb-user}" security-realm="ejb-security-realm"> ...

works fine:

<remote-outbound-connection name="remote-ejb-connection" outbound-socket-binding-ref="remote-ejb-1" username="someUser" security-realm="ejb-security-realm">

This works fine in the jboss-ejb-client.xml however so the behaviour is not consistent.