code: private boolean exists(FTPClient client, Path file) {
      try {
        return getFileStatus(client, file) != null;
      } catch (FileNotFoundException fnfe) {
        return false;
      } catch (IOException ioe) {
        throw new FTPException("Failed to get file status", ioe);
      }
    }
docs: Convenience method, so that we don't open a new connection when using this
  method from within another method. Otherwise every API invocation incurs
  the overhead of opening/closing a TCP connection.