code: public static byte[] packEntry(File file) {
      log.trace("Compressing '{}' into a ZIP file with single entry.", file);
  
      ByteArrayOutputStream result = new ByteArrayOutputStream();
      try {
        ZipOutputStream out = new ZipOutputStream(result);
        ZipEntry entry = ZipEntryUtil.fromFile(file.getName(), file);
        InputStream in = new BufferedInputStream(new FileInputStream(file));
        try {
          ZipEntryUtil.addEntry(entry, in, out);
        }
        finally {
          IOUtils.closeQuietly(in);
        }
        out.close();
      }
      catch (IOException e) {
        throw ZipExceptionUtil.rethrow(e);
      }
      return result.toByteArray();
    }
docs: Compresses the given file into a ZIP file with single entry.
  
  @param file file to be compressed.
  @return ZIP file created.