/**
  * Append a new quantity index to the passed in 'qtys' array when a match Magento
  * order item is found in the pass in items collection.
  * @param  OrderEvents\IOrderItem $orderItem
  * @param  Varien_Data_Collection $items
  * @param  array $qtys
  * @return self
  */
 protected function _appendToQtyArray(OrderEvents\IOrderItem $orderItem, Varien_Data_Collection $items, array $qtys)
 {
     $item = $items->getItemByColumnValue('sku', $orderItem->getItemId());
     if ($item) {
         // Magento only support integer quantity
         $qtys[$item->getItemId()] = (int) $orderItem->getQuantity();
     }
     return $qtys;
 }