code: public static VerificationCodePayload from(Map<String, String> queryStringParameters) {
          VerificationCodePayload payload = new VerificationCodePayload();
          payload.setCode(queryStringParameters.get("code"));
          payload.setState(queryStringParameters.get("state"));
          payload.setError(queryStringParameters.get("error"));
          return payload;
      }
docs: Extracts code and state from Map object. This method is supposed to be used in AWS lambda functions.
  See also {@link com.github.seratch.jslack.app_backend.vendor.aws.lambda.request.ApiGatewayRequest}