Author: Hugo Briand (briand@ekino.com)
Inheritance: extends Symfony\Component\EventDispatcher\Event
 /**
  * @param ProductInterface  $product
  * @param CurrencyInterface $currency
  * @param bool              $vat
  * @param int               $quantity
  * @param float             $price
  */
 public function __construct(ProductInterface $product, CurrencyInterface $currency, $vat, $quantity, $price)
 {
     parent::__construct($product, $currency, $vat, $quantity);
     $this->price = $price;
 }