How to use the @feathersjs/express.rest.formatter function in @feathersjs/express

}, pick(authSettings, ...INCLUDE_KEYS), providerSettings, omit(options, ...EXCLUDE_KEYS));

    // Set callback defaults based on provided path
    oauth2Settings.callbackPath = oauth2Settings.callbackPath || `${oauth2Settings.path}/callback`;
    oauth2Settings.callbackURL = oauth2Settings.callbackURL || makeUrl(oauth2Settings.callbackPath, app);

    if (!oauth2Settings.clientID) {
      throw new Error(`You must provide a 'clientID' in your authentication configuration or pass one explicitly`);
    }

    if (!oauth2Settings.clientSecret) {
      throw new Error(`You must provide a 'clientSecret' in your authentication configuration or pass one explicitly`);
    }

    const Verifier = options.Verifier || DefaultVerifier;
    const formatter = options.formatter || rest.formatter;
    const handler = options.handler || defaultHandler(oauth2Settings);
    const errorHandler = typeof options.errorHandler === 'function' ? options.errorHandler(oauth2Settings) : defaultErrorHandler(oauth2Settings);

    // register OAuth middleware
    debug(`Registering '${name}' Express OAuth middleware`);
    app.get(oauth2Settings.path, auth.express.authenticate(name, omit(oauth2Settings, 'state')));
    app.get(
      oauth2Settings.callbackPath,
      _callbackAuthenticator(authSettings),
      auth.express.authenticate(name, omit(oauth2Settings, 'state')),
      handler,
      errorHandler,
      auth.express.emitEvents(authSettings, app),
      auth.express.setCookie(authSettings),
      auth.express.successRedirect(),
      auth.express.failureRedirect(authSettings),