code: public Connection<?> completeConnection(OAuth1ConnectionFactory<?> connectionFactory, NativeWebRequest request) {
  		String verifier = request.getParameter("oauth_verifier"); 
  		AuthorizedRequestToken requestToken = new AuthorizedRequestToken(extractCachedRequestToken(request), verifier);
  		OAuthToken accessToken = connectionFactory.getOAuthOperations().exchangeForAccessToken(requestToken, null);
  		return connectionFactory.createConnection(accessToken);
  	}
docs: Complete the connection to the OAuth1 provider.
  @param connectionFactory the service provider's connection factory e.g. FacebookConnectionFactory
  @param request the current web request
  @return a new connection to the service provider