code: public static String getReqOneNodeVal(final Node el, final String name)
        throws SAXException {
      String str = getOneNodeVal(el, name);
  
      if ((str == null) || (str.length() == 0)) {
        throw new SAXException("Missing property value: " + name);
      }
  
      return str;
    }
docs: Get the value of an element. We expect 1 child node otherwise we raise an
  exception.
  
  @param el          Node whose value we want
  @param name        String name to make exception messages more readable
  @return String     node value
  @throws SAXException