private function getStartGoogleAuthenticationResponse()
    {
        $response = new Redirection($this->getRequest());

        $currentUser = Users::getCurrent();
        try {
            // Set up the redirection to Google's authentication URL.
            $identityProvider = new GoogleIdentityProvider;
            $response->setNextUrl($identityProvider->getAuthenticationUrl());
        } catch (AuthenticationException $exception) {
            $response->setErrorMessage('Google authentication did not succeed.');
            $response->setNextUrl($this->getRequest()->getCurrentUrl());
        }

        return $response;
    }