Airship\Engine\Hail::postSignedJSON PHP Method

    public function postSignedJSON(string $url, SignaturePublicKey $publicKey, array $params = [])
    {
        $response = $this->client->post($url, $this->params($params, $url));
        if ($response instanceof Response) {
            return $this->parseSignedJSON($response, $publicKey);
        }
        return null;
    }