docs: public static String getAttributeValueOrNull(final Node elementNode, final String attrName)
      {
          if (null == elementNode || null == elementNode.getAttributes())
          {
              return null;
          }
  
          final Node attrNode = elementNode.getAttributes().getNamedItemNS(null, attrName);
          if (null == attrNode)
          {
              return null;
          }
  
          return attrNode.getNodeValue();
      }