private byte[] buildFinalXML(Document original, Set<ExtendElement> elements) throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
Element root = (Element)original.getRootElement().clone();
root.removeContent();
Document doc = new Document((Element)root.detach(),
original.getDocType(), original.getBaseURI());
for(ExtendElement element : elements) {
root.addContent(element.node.detach());
}