code: public static void setVerificationHeaders(HttpServletResponse response, File file)
    throws IOException {
      response.setHeader(TransferFsImage.CONTENT_LENGTH,
          String.valueOf(file.length()));
      MD5Hash hash = MD5FileUtils.readStoredMd5ForFile(file);
      if (hash != null) {
        response.setHeader(TransferFsImage.MD5_HEADER, hash.toString());
      }
    }
docs: Set headers for content length, and, if available, md5.
  @throws IOException