tree.startDocument(URI.create("http://example.com/"));
tree.addStartElement(pr_error);
tree.startContent();
tree.addStartElement(pr_code);
tree.startContent();
tree.addText("" + status.getCode());
tree.addEndElement();
tree.addStartElement(pr_message);
tree.startContent();
tree.addText("Bad request: " + msg);
tree.addEndElement();