public static String relativePath(final File root, File path) {
    String rc = FileUtil.getRelativePath(root, path);
    if (rc == null) {
      throw new IllegalArgumentException("The file " + path + " cannot be made relative to " + root);
    }
    return rc.replace(File.separatorChar, '/');
  }
public static String relativePath(final File root, File path)