code: public void stop(StopConfiguration configuration) throws AppEngineException {
      Preconditions.checkNotNull(configuration);
      HttpURLConnection connection = null;
      String host = configuration.getHost() != null ? configuration.getHost() : DEFAULT_HOST;
      int port = configuration.getPort() != null ? configuration.getPort() : DEFAULT_PORT;
      URL adminServerUrl = null;
      try {
        adminServerUrl = new URL("http", host, port, "/_ah/admin/quit");
        connection = (HttpURLConnection) adminServerUrl.openConnection();
        connection.setDoOutput(true);
        connection.setDoInput(true);
        connection.setRequestMethod("POST");
        connection.getOutputStream().write('\n');
        connection.disconnect();
        int responseCode = connection.getResponseCode();
        if (responseCode < 200 || responseCode > 299) {
          throw new AppEngineException(
              adminServerUrl + " responded with " + connection.getResponseMessage() + ".");
        }
      } catch (IOException ex) {
        throw new AppEngineException("Error connecting to " + adminServerUrl, ex);
      } finally {
        if (connection != null) {
          try {
            connection.getInputStream().close();
          } catch (IOException ignore) {
            // ignored
          }
        }
      }
    }
docs: Stops the local development server.