code: public static void packEntry(File fileToPack, File destZipFile, NameMapper mapper) {
      packEntries(new File[] { fileToPack }, destZipFile, mapper);
    }
docs: Compresses the given file into a ZIP file.
  <p>
  The ZIP file must not be a directory and its parent directory must exist.
  
  @param fileToPack
  file that needs to be zipped.
  @param destZipFile
  ZIP file that will be created or overwritten.
  @param mapper
  call-back for renaming the entries.