public function addCustomProperty($propertiesList)
    {

        if ($propertiesList == '')
            throw new Exception('Properties not specified');


        //build URI to merge Docs
        $strURI = Product::$baseProductUri . '/slides/' . $this->getFileName() . '/documentProperties';

        $put_data = json_encode($propertiesList);

        //sign URI
        $signedURI = Utils::sign($strURI);

        $responseStream = Utils::processCommand($signedURI, 'PUT', 'json', $put_data);

        $json = json_decode($responseStream);

        return $json;
    }