private String getHostNameFromQuery(Request request) {
    Matcher matcher = HOSTNAME_PATTERN.matcher(request.getURI());
    if(matcher.find()) {
      return matcher.group(1);
    }
    return null;
  }
Returns hostname from the query string of the request
@param request
@return
ambari-server/src/main/java/org/apache/ambari/server/audit/request/eventcreator/HostEventCreator.java