docs: public Document stringToDom(String xmlSource) throws S2SException {
          try {
              DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
              factory.setNamespaceAware(true);
              DocumentBuilder builder = factory.newDocumentBuilder();
              return builder.parse(new InputSource(new StringReader(xmlSource)));
          }
          catch (SAXException | IOException | ParserConfigurationException ex) {
              throw new S2SException(ex.getMessage(), ex);
          }
      }