code: public static void unpack(InputStream is, File outputDir, NameMapper mapper, Charset charset) {
      log.debug("Extracting {} into '{}'.", is, outputDir);
      iterate(is, new Unpacker(outputDir, mapper), charset);
    }
docs: Unpacks a ZIP stream to the given directory.
  <p>
  The output directory must not be a file.
  
  @param is
  inputstream for ZIP file.
  @param outputDir
  output directory (created automatically if not found).
  @param mapper
  call-back for renaming the entries.
  @param charset
  charset to use when unpacking the stream