code: private void setDateAndCacheHeaders(HttpResponse response, File fileToCache) {
          response.headers().set(HttpConst.DATE, DateKit.gmtDate());
          // Add cache headers
          if (httpCacheSeconds > 0) {
              response.headers().set(HttpConst.EXPIRES, DateKit.gmtDate(LocalDateTime.now().plusSeconds(httpCacheSeconds)));
              response.headers().set(HttpConst.CACHE_CONTROL, "private, max-age=" + httpCacheSeconds);
              if (null != fileToCache) {
                  response.headers().set(HttpConst.LAST_MODIFIED, DateKit.gmtDate(new Date(fileToCache.lastModified())));
              } else {
                  response.headers().set(HttpConst.LAST_MODIFIED, DateKit.gmtDate(LocalDateTime.now().plusDays(-1)));
              }
          }
      }
docs: Sets the Date and Cache headers for the HTTP Response
  
  @param response    HTTP response
  @param fileToCache file to extract content type