How to get lineItems.product option value - shopware6

Question

I want to make a json field of an order to our API. The issue is, that it can't find productNumber.
I've made search of an order with the association:
$this->context = $context;
$criteria = new Criteria([$orderId]);
$criteria->addAssociation(OrderExtension::DSM_INTEGRATION_ORDER);
$criteria->addAssociation('addresses');
$criteria->addAssociation('billingAddress.country');
$criteria->addAssociation('transactions.paymentMethod');
$criteria->addAssociation('deliveries.shippingMethod');
$criteria->addAssociation('deliveries.shippingOrderAddress.country');
$criteria->addAssociation('lineItems.product');
$criteria->addAssociation('lineItems.product.tags');
$criteria->addAssociation('lineItems.product.options');
$criteria->addAssociation('orderCustomer.customer');
$result = $this->orderRepository->search($criteria, $context);
However, the result has no productNumber, when I receive the type "customized-products"
enter image description here
it use uses OrderEntity.
I want the productNumber, when the order is a type "customized-products". I expect, the association is something like "lineItems.product.customized_product", but I have yet to find the correct one.
Note. We use "productOswag_customized_products_templateptions"

Answer 1

To retrieve the product number starting from the order entity, via the order line items, you would have to proceed similar to this:
$criteria = new Criteria();
$criteria->addAssociation('lineItems.product');
$result = $this->orderRepository->search($criteria, $context);
/** #var OrderEntity|null $order */
$order = $result->first();
/** #var OrderLineItemCollection|null $lineItems */
$lineItems = $order->getLineItems();
/** #var OrderLineItemEntity|null $lineItem */
$lineItem = $lineItems->first();
/** #var ProductEntity|null $product */
$product = $lineItem->getProduct();
$productNumber = $product->getProductNumber();
Note the getters might return null at any point, e.g. due to the product having been deleted in the meanwhile or the line item being a discount, so add some checks for that case.