private static List<String> extend(final List<String> paths) {
    if (paths == null) {
      return null;
    }
    final Set<String> extended = new HashSet<String>();
    for (final String path : paths) {
      extended.add(path);
      if (path.startsWith(DEEP_PREFIX)) {
        extended.add(path.substring(DEEP_PREFIX.length()));
      }
    }
    return new ArrayList<String>(extended);
  }