private boolean checkUpToDate(@NotNull Url url, @NotNull String path, @NotNull String header) {
    File file = new File(path + "." + header);
    try {
      return isUpToDate(url, file, header);
    }
    catch (IOException e) {
      // in case of an error, don't bother with update for the next UPDATE_DELAY milliseconds
      //noinspection ResultOfMethodCallIgnored
      new File(path).setLastModified(System.currentTimeMillis());
      return true;
    }
  }
private boolean checkUpToDate(@NotNull Url url, @NotNull String path, @NotNull String header)