Magento 2 get shipped items in sales_order_shipment_save_after event

Question

I want the items that are shipped in the "sales_order_shipment_save_after" event(Not all the ordered items,only the currently shipped items). How can I do it. Here is my code. This code gives shipment id, but the shipment items are not returned.

class ProcessShipment implements ObserverInterface
{


     /**
     * @var eventManager
     */
    protected $_eventManager;

    /**
     * @var ObjectManagerInterface
     */
    protected $_objectManager;

    protected $_shipmentItemCollectionFactory;


    public function __construct(
        \Magento\Framework\Event\Manager $eventManager,
        \Magento\Framework\ObjectManagerInterface $objectManager,
        \Magento\Sales\Model\ResourceModel\Order\Shipment\Item\CollectionFactory $shipmentItemCollectionFactory,
        \Magento\Store\Model\StoreManagerInterface $storeManager       
    ) {
        $this->_eventManager = $eventManager;
        $this->_objectManager = $objectManager;  
        $this->_storeManager = $storeManager;        
           }



    public function execute(Observer $observer)
    {       

        $shipment = $observer->getEvent()->getShipment();
        $order = $shipment->getOrder();
        $items = $this->_shipmentItemCollectionFactory->create()->setShipmentFilter($shipment->getId());

        foreach($items as $item){    
            $id = $item->getProductId();    
        }

}

Answer 1

class ProcessShipment implements ObserverInterface
{


     /**
     * @var eventManager
     */
    protected $_eventManager;

    /**
     * @var ObjectManagerInterface
     */
    protected $_objectManager;

    protected $_shipmentItemCollectionFactory;


    public function __construct(
        \Magento\Framework\Event\Manager $eventManager,
        \Magento\Framework\ObjectManagerInterface $objectManager,
        \Magento\Sales\Model\ResourceModel\Order\Shipment\Item\CollectionFactory $shipmentItemCollectionFactory,
        \Magento\Store\Model\StoreManagerInterface $storeManager       
    ) {
        $this->_eventManager = $eventManager;
        $this->_objectManager = $objectManager;  
        $this->_storeManager = $storeManager;        
           }



    public function execute(Observer $observer)
    {       

        $shipment = $observer->getEvent()->getShipment();

        foreach ($shipment->getItemsCollection() as $item) {    
            $id = $item->getOrderItem()->getProductId();    
        }
    }

}