QName qname = new QName("http://www.w3.org/2005/Atom", "atom");
qnameMap.registerMapping(qname, DefaultRelation.class);
// we need the replacer because
// xstream replaces an _ with __ (two underscore) more information at
// http://xstream.codehaus.org/faq.html#XML_double_underscores
XmlFriendlyReplacer replacer = new XmlFriendlyReplacer("$", "_");
helper = new XStreamHelper(new StaxDriver(qnameMap, replacer), enhancer);
}