Ahh found the problem. You're using xs:any which is always an issue with jaxb and needs to be handled.
When creating an item, you'll need to use the ObjectFactory.create..... which returns a JAXBElement<sometype>
When accessing, you'll have to type cast the object to a JAXBElement<sometype>
you'll probably also want to use a tool like tcpmon to verify the content on the wire against the wsdl/xsd and make adjustments (if necessary) to the object factory