docs: private @Nullable FileInfo getShardFileInfo(File file) {
      FileInfo info = FileInfo.fromFile(file);
      if (info == null) {
        return null; // file with incorrect name/extension
      }
      File expectedDirectory = getSubdirectory(info.resourceId);
      boolean isCorrect = expectedDirectory.equals(file.getParentFile());
      return isCorrect ? info : null;
    }