Good news: I've wired @MTOM all the way down to the JAXBAttachmentMarshaller.
Bad news: I introduced a bit of a dependency from the JAXBDataBinding on JAXWS, by actually using the MTOMFeature class to carry the facts downstream. If this really bothers someone, it can clearly be replaced by some class of ours. As usual, I'm not a fan of the 'big bag of properties', so I'd make AbstractDataBinding responsible for hanging onto the boolean and integer that are at issue here.
