code: public final OAuthCredentialsResponse execute() throws IOException {
      HttpRequestFactory requestFactory = transport.createRequestFactory();
      HttpRequest request =
          requestFactory.buildRequest(usePost ? HttpMethods.POST : HttpMethods.GET, this, null);
      createParameters().intercept(request);
      HttpResponse response = request.execute();
      response.setContentLoggingLimit(0);
      OAuthCredentialsResponse oauthResponse = new OAuthCredentialsResponse();
      UrlEncodedParser.parse(response.parseAsString(), oauthResponse);
      return oauthResponse;
    }
docs: Executes the HTTP request for a temporary or long-lived token.
  
  @return OAuth credentials response object