protected function head($path, array $parameters = array(), $requestHeaders = array())
    {
        if (array_key_exists('ref', $parameters) && is_null($parameters['ref'])) {
            unset($parameters['ref']);
        }

        $response = $this->client->getHttpClient()->request($path, null, 'HEAD', $requestHeaders, array(
            'query' => $parameters
        ));

        return $response;
    }