As usual - once I posted the problem a solution appeared - as if by Magic. That's StackOverflow for you.
From JAXB unmarshal with declared type does not populate the resulting object with data
public class NamespaceFilter extends XMLFilterImpl {
private static final String NAMESPACE = "http://aschema/";
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
super.endElement(NAMESPACE, localName, qName);
}
@Override
public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {
super.startElement(NAMESPACE, localName, qName, atts);
}
}
...
// Create the XMLFilter
XMLFilter filter = new NamespaceFilter();
// Set the parent XMLReader on the XMLFilter
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xr = sp.getXMLReader();
filter.setParent(xr);
// Set UnmarshallerHandler as ContentHandler on XMLFilter
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
UnmarshallerHandler unmarshallerHandler = unmarshaller.getUnmarshallerHandler();
filter.setContentHandler(unmarshallerHandler);
// Parse the XML
filter.parse(new InputSource(r));
//Object result = unmarshallerHandler.getResult();
T t = (T) unmarshallerHandler.getResult();