/**
  * singleton pattern
  *
  * @return PlentyItemDataPushStock
  */
 public static function getInstance()
 {
     if (!isset(self::$instance) || !self::$instance instanceof PlentyItemDataPushStock) {
         self::$instance = new PlentyItemDataPushStock();
     }
     return self::$instance;
 }
 /**
  * push items to stock data objects
  *
  * @param int $itemId
  * @param int $priceId
  */
 private function push2StockStack($itemId, $priceId)
 {
     if ($itemId > 0 && $priceId > 0 && $this->warehouseId > 0) {
         PlentyItemDataPushStock::getInstance()->setItemId($itemId)->setPriceId($priceId)->setAttributeValueSetId(0)->setWarehouseId($this->warehouseId)->pushItemData2Stack(2);
     } else {
         $this->getLogger()->crit(__FUNCTION__ . ' I miss some data - itemId: ' . $itemId . ' priceId: ' . $priceId . ' warehouseId: ' . $this->warehouseId);
     }
 }