code: public String queryDescriptorValue(String xpathQuery) {
          if (descriptorDom != null) {
              String value = (String)getProperty(xpathQuery);
              if (value == null) {
                  value = XmlUtils.selectSingleNodeValue(descriptorDom, xpathQuery);
              }
  
              return value;
          } else {
              return null;
          }
      }
docs: Queries a single descriptor node text value. First looks in the properties, if not found it executes the XPath
  query.