code: public static String parseXml(String xml, String expression) throws ParserConfigurationException, IOException, XPathExpressionException, SAXException {
          DocumentBuilder builder = ResourceLoader.getDocumentBuilder();
          Document document;
          try {
              document = builder.parse(new InputSource(new StringReader(xml)));
          } catch (SAXException e) {
              throw new RuntimeException(RESPONSE_IS_NOT_WELL_FORMED + xml, e);
          }
          XPath xPath = XPathFactory.newInstance().newXPath();
          return xPath.compile(expression).evaluate(document);
      }
docs: Parse the content of the given xml input and evaluates the given XPath expression.
  
  @param xml        The xml source.
  @param expression The XPath expression.
  @return Evaluate the XPath expression and return the result as a String.
  @throws ParserConfigurationException
  @throws IOException
  @throws XPathExpressionException
  @throws SAXException