code: @Pure
  	public static File getJarFile(URL url) {
  		if (isJarURL(url)) {
  			final String path = url.getPath();
  			final int idx = path.lastIndexOf(JAR_URL_FILE_ROOT);
  			if (idx >= 0) {
  				return new File(decodeHTMLEntities(path.substring(idx + 1)));
  			}
  		}
  		return null;
  	}
docs: Replies the file part of the jar-scheme URL.
  
  <p>If the input URL is {@code jar:file:/path1/archive.jar!/path2/file},
  the output of this function is {@code /path2/file}.
  
  @param url the URL to test.
  @return the file in the given URL, or <code>null</code>
  if the given URL does not use jar scheme.