code: private void setDateAndCacheHeaders(final HttpResponse response) {
      final SimpleDateFormat dateFormatter = new SimpleDateFormat(HTTP_DATE_FORMAT, Locale.US);
      dateFormatter.setTimeZone(TimeZone.getTimeZone(HTTP_DATE_GMT_TIMEZONE));
  
      // Date header
      final Calendar time = new GregorianCalendar();
      response.headers().set(DATE, dateFormatter.format(time.getTime()));
  
      // Add cache headers
      time.add(Calendar.SECOND, HTTP_CACHE_SECONDS);
      response.headers().set(EXPIRES, dateFormatter.format(time.getTime()));
      response.headers().set(CACHE_CONTROL, "private, max-age=" + HTTP_CACHE_SECONDS);
      response.headers().set(LAST_MODIFIED, dateFormatter.format(new Date(startupTime)));
    }
docs: Sets the Date and Cache headers for the HTTP Response
  
  @param response HTTP response