How to get UPC of item via GetSellerList call in eBay Trading API [Java] – Ebay API

I’m trying to get UPC of item returned by GetSellerList call using eBay Trading API.

I’m able to successfully execute the API call using this code:

public void getSellerItemsList() throws ApiException, SdkException, Exception
{
    String EBayProfile = "XXXXXXXXXXXX";
    String sellerID = "XXXXXXXXXXXXXX"; 
    ApiContext apiContext = getAPIContext(EBayProfile);

    GetSellerListCall getSellerList  = new GetSellerListCall ();
    getSellerList.setApiContext(apiContext);



    DetailLevelCodeType[] detailLevelCodeType = new DetailLevelCodeType[1];
    detailLevelCodeType[0] = DetailLevelCodeType.RETURN_ALL;
    getSellerList.setDetailLevel(detailLevelCodeType);






    Calendar fromTime = Calendar.getInstance();
    fromTime.add(Calendar.DAY_OF_MONTH, -3);

    Calendar toTime = Calendar.getInstance();
    toTime.setTime(Calendar.getInstance().getTime());


    TimeFilter startTimeFilter = new TimeFilter(fromTime, toTime);
    getSellerList.setStartTimeFilter(startTimeFilter);


    getSellerList.setUserID(sellerID);
    getSellerList.setEnableCompression(true);
    WarningLevelCodeType warningLevel = WarningLevelCodeType.HIGH;
    getSellerList.setWarningLevel(warningLevel);


    PaginationType paginationType = new PaginationType();
    paginationType.setEntriesPerPage(199);
    paginationType.setPageNumber(1);


    ItemType[] items = getSellerList.getEntireSellerList();




    for (ItemType item : items) {
        System.out.println("nTitle: " + item.getTitle());


        // For some reason this value is always equal to null (never prints)
        if (item.getAttributeArray() != null) {

            AttributeArrayType attributeType = item.getAttributeArray();
            System.out.println("Attributes length: " + attributeType.getAttributeLength());

        }


        // For some reason this value is always equal to null (never prints)
        if (item.getProductListingDetails() != null) {
            UPC = item.getProductListingDetails().getUPC();
            System.out.println("UPC: " + UPC);  
        }  

        // For some reason this value is always equal to null (never prints)
        if (item.getVariations() != null) {
            VariationsType itemVariations = item.getVariations();

            for (int x = 0; x < itemVariations.getVariationLength(); x++) {
                VariationType variation = itemVariations.getVariation(x);
                VariationProductListingDetailsType variationListingDetails = variation.getVariationProductListingDetails();
                UPC = variationListingDetails.getUPC(); // UPC always missing

            }

        }




        // For some reason this value is always equal to null (never prints)
        if (item.getItemSpecifics() != null) {
            NameValueListArrayType itemSpecifics = item.getItemSpecifics();
            NameValueListType[] nameValueList = itemSpecifics.getNameValueList();


            }
        }
    }


}

Call executes successfully but the UPC is empty (no matter where I try to extract it from, as seen in previous code).

eBay Docs clearly state this call returns UPC.

What am I doing wrong?