Blackfire\Player\Guzzle\RequestFactory::createBody PHP Метод

    private function createBody(ValueBag $values, $parameters, &$headers, $isJson)
    {
        if (!$parameters) {
            return;
        }
        if ($isJson) {
            $headers['Content-Type'] = 'application/json';
        } else {
            $headers['Content-Type'] = 'application/x-www-form-urlencoded';
        }
        if (is_string($parameters)) {
            return $parameters;
        }
        if ($isJson) {
            return Psr7\stream_for(json_encode($parameters));
        } else {
            return Psr7\stream_for(http_build_query($parameters, null, '&'));
        }
    }