magento-test/app/code/Magento/SalesGraphQl/etc/graphql/di.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\SalesGraphQl\Model\TypeResolver\OrderItem">
        <arguments>
            <argument name="productTypeMap" xsi:type="array">
                <item name="default" xsi:type="string">OrderItem</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\SalesGraphQl\Model\TypeResolver\InvoiceItem">
        <arguments>
            <argument name="productTypeMap" xsi:type="array">
                <item name="default" xsi:type="string">InvoiceItem</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\SalesGraphQl\Model\TypeResolver\CreditMemoItem">
        <arguments>
            <argument name="productTypeMap" xsi:type="array">
                <item name="default" xsi:type="string">CreditMemoItem</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\SalesGraphQl\Model\TypeResolver\ShipmentItem">
        <arguments>
            <argument name="productTypeMap" xsi:type="array">
                <item name="default" xsi:type="string">ShipmentItem</item>
            </argument>
        </arguments>
    </type>
    <preference for="Magento\SalesGraphQl\Model\Shipment\Item\FormatterInterface" type="Magento\SalesGraphQl\Model\Shipment\Item\ShipmentItemFormatter"/>
    <type name="Magento\SalesGraphQl\Model\Shipment\ItemProvider">
        <arguments>
            <argument name="formatters" xsi:type="array">
                <item name="default" xsi:type="object">Magento\SalesGraphQl\Model\Shipment\Item\ShipmentItemFormatter\Proxy</item>
            </argument>
        </arguments>
    </type>
</config>