Omnipay\PayPal\Message\AbstractRequest::sendData PHP Method

    public function sendData($data)
    {
        $httpRequest = $this->httpClient->post($this->getEndpoint(), null, http_build_query($data, '', '&'));
        $httpRequest->getCurlOptions()->set(CURLOPT_SSLVERSION, 6);
        // CURL_SSLVERSION_TLSv1_2 for libcurl < 7.35
        $httpResponse = $httpRequest->send();
        return $this->createResponse($httpResponse->getBody());
    }