google oauth2 redirect

        Credential credential = new Credential.Builder(BearerToken.authorizationHeaderAccessMethod())
        .addRefreshListener(new CredentialStoreRefreshListener(stripesActionBeanContext.getUser().getUserId(),
                new AppEngineCredentialStore()))
        .setJsonFactory(new JacksonFactory())
        .setTokenServerUrl(new GenericUrl("https://accounts.google.com/o/oauth2/token"))
        .setClientAuthentication(
                new ClientParametersAuthentication(
                        Constants.GOOGLE_API_KEY,
                        Constants.GOOGLE_API_SECRET))
        .setTransport(new UrlFetchTransport())
        .build();

        AppEngineCredentialStore appEngineCredentialStore =
            new AppEngineCredentialStore();

        if (! appEngineCredentialStore.load(stripesActionBeanContext.getUser().getUserId(), credential)) {
            log.debug("calling AuthorizationCodeRequestUrl");

            String url =
                    new AuthorizationCodeRequestUrl("https://accounts.google.com/o/oauth2/auth",
                            Constants.GOOGLE_API_KEY)
                        .setRedirectUri(Constants
                                .googleOJCCallbackUri(stripesActionBeanContext.getRequest().getScheme(),
                                        stripesActionBeanContext.getRequest().getServerName(),
                                        stripesActionBeanContext.getRequest().getServerPort()))
                        .setScopes(Collections.singletonList("https://www.googleapis.com/auth/urlshortener"))
                        .setState(stripesActionBeanContext.getRequest().getRequestURI())
                        .set("approval_prompt", "force")
                        .set("access_type", "offline")
                        .build();

            log.debug("redirect url: {}", url);

            return (new RedirectResolution(url));
        }