@Nullable
  private static File getMapDirectory() {
    Path dir = PathManager.getConfigDir().resolve("migration");
    try {
      Files.createDirectories(dir);
    }
    catch (IOException e) {
      LOG.error("cannot create directory: " + dir, e);
      return null;
    }
    return dir.toFile();
  }
@Nullable
  private static File getMapDirectory()