code: private static void setDateHeader(final FullHttpResponse response) {
      final SimpleDateFormat dateFormatter = new SimpleDateFormat(HTTP_DATE_FORMAT, Locale.US);
      dateFormatter.setTimeZone(TimeZone.getTimeZone(HTTP_DATE_GMT_TIMEZONE));
  
      final Calendar time = new GregorianCalendar();
      response.headers().set(DATE, dateFormatter.format(time.getTime()));
    }
docs: Sets the Date header for the HTTP response
  
  @param response
  HTTP response