code: public static long zip(File directory, File outputZipFile) throws IOException
    {
      if (!isZip(outputZipFile.getName())) {
        log.warn("No .zip suffix[%s], putting files from [%s] into it anyway.", outputZipFile, directory);
      }
  
      try (final FileOutputStream out = new FileOutputStream(outputZipFile)) {
        return zip(directory, out);
      }
    }
docs: Zip the contents of directory into the file indicated by outputZipFile. Sub directories are skipped
  
  @param directory     The directory whose contents should be added to the zip in the output stream.
  @param outputZipFile The output file to write the zipped data to
  
  @return The number of bytes (uncompressed) read from the input directory.
  
  @throws IOException