newsupernova/vendor/magento/module-configurable-product/etc/frontend/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\ConfigurableProduct\Model\ResourceModel\Attribute\OptionSelectBuilderInterface">
        <plugin name="Magento_ConfigurableProduct_Plugin_Model_ResourceModel_Attribute_InStockOptionSelectBuilder" type="Magento\ConfigurableProduct\Plugin\Model\ResourceModel\Attribute\InStockOptionSelectBuilder"/>
    </type>
    <type name="Magento\Catalog\Model\Product">
        <plugin name="product_identities_extender" type="Magento\ConfigurableProduct\Model\Plugin\Frontend\ProductIdentitiesExtender" />
    </type>
</config>