@Nullable private static String readXmlFile(@Nullable URL url){
  String xmlFileContent=null;
  if (url != null) {
    try {
      xmlFileContent=UrlUtil.loadText(url);
    }
 catch (    IOException e) {
      LOG.error(e);
    }
  }
  return xmlFileContent;
}

@ Nullable private static String readXmlFile ( @ Nullable URL url ) { String xmlFileContent = null ; if ( url != null ) { try { xmlFileContent = UrlUtil . loadText ( url ) ; } catch ( IOException e ) { LOG . error ( e ) ; } } return xmlFileContent ; }
read the xml file directly as a simple string . if there is any exception , just return null .
