code: public Client loginWithVerifier(String verifier) {
          Token token = service.getAccessToken(requestToken, new Verifier(verifier));
          return loginWithAccessToken(token.getToken(), token.getSecret());
      }
docs: Retrieve a client instance for making calls as the user who gave
  permission in UserVoice site.
  
  @param verifier
  the verifier that was passed as a GET paramter or received in
  Out-Of-Band fashion
  @return The client for making calls as the authorized and verified user