protected function addRequestBody()
    {
        if (! empty($this->payload['parameters'])) {
            if (in_array($this->method, ['DELETE', 'PATCH', 'POST', 'PUT'])) {
                $this->addCurlOption(CURLOPT_POSTFIELDS, $this->formattedRequestBody());
            } elseif (is_array($this->payload['parameters'])) {
                // append parameters in the url
                $this->payload['url'] = sprintf('%s?%s', $this->payload['url'], $this->formattedRequestBody());
            }
        }
    }