code: public RequestToken retrieveRequestToken(String callbackURL) {
          OAuthConsumer consumer = new DefaultOAuthConsumer(info.key.key, info.key.secret);
          try {
              provider.retrieveRequestToken(consumer, callbackURL);
              return new RequestToken(consumer.getToken(), consumer.getTokenSecret());
          } catch (OAuthException ex) {
              throw new RuntimeException(ex);
          }
      }
docs: Request the request token and secret.
  
  @param callbackURL the URL where the provider should redirect to (usually a URL on the current app)
  @return A Right(RequestToken) in case of success, Left(OAuthException) otherwise