/**
  * injecting shipment data into order shipment item collection
  * @param  array
  * @param  Mage_Sales_Model_Order_Item
  * @return self
  */
 protected function _injectShipmentItems(array $data, Mage_Sales_Model_Order_Item $item)
 {
     if (!$this->_items) {
         $this->_items = new Varien_Data_Collection();
     }
     $shipmentItem = $this->factory->getNewSalesOrderShipmentItem($data);
     $shipmentItem->setOrderItem($item)->setShipment($this);
     $this->_items->addItem($shipmentItem);
     return $this;
 }