@Nullable
    private String getCommonFragment(int count) {
      String commonFragment = null;
      for (String[] path : myPaths) {
        int index = getFragmentIndex(path, count);
        if (index == -1) return null;
        if (commonFragment == null) {
          commonFragment = path[index];
          continue;
        }
        if (!Comparing.strEqual(commonFragment, path[index], SystemInfo.isFileSystemCaseSensitive)) return null;
      }
      return commonFragment;
    }
@Nullable
    private String getCommonFragment(int count)