JAX-WS Provider returning JAXBSource with attachment

I am trying to return a JAXBSource payload from a JAX-WS Provider;
the JAXBSource's Marshaller has a custom AttachmentMarshaller
that puts the attachments into the MessageContext's
OUTBOUND_MESSAGE_ATTACHMENTS Map

the problem is that the attachments are not included in the response
multipart SOAP message

however, if I transform the same JAXBSource result payload
into a DOMSource, and return this DOMSource from the Provider#invoke()
method,
then the attachments are included in the response multipart SOAP message!

I think the problem is that
when I return the JAXBSource
the attachments are added "too late"
(when the JAXBSource is processed by the CXF runtime, outside of the
Provider#invoke() method)
to the MessageContext

am I right, if I think that this means
that CXF currently does not support
JAXBSource payload results *with attachments*?

which means that we have to build an unnecessary DOM tree in these cases...