code: public function normalize($item, $format = null, array $context = [])
      {
          $data = parent::normalize($item, $format, $context);
  
          if ($this->contextHasGroup('Summary', $context)) {
              $order = $item->getOrder();
  
              $received = 0;
              foreach ($order->getDeliveries() as $delivery) {
                  foreach ($delivery->getItems() as $di) {
                      if ($di->getOrderItem() === $item) {
                          $received += $di->getQuantity();
                      }
                  }
              }
  
              $formatter = $this->getFormatter();
  
              $data = array_replace($data, [
                  'designation' => $item->getDesignation(),
                  'net_price'   => $formatter->currency($item->getNetPrice(), $order->getCurrency()->getCode()),
                  'ordered'     => $formatter->number($item->getQuantity()),
                  'received'    => $formatter->number($received),
              ]);
          }
  
          return $data;
      }
docs: @inheritdoc
  
  @param SupplierOrderItemInterface $item