magento-test/app/code/Magento/Sitemap/etc/email_templates.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:module:Magento_Email:etc/email_templates.xsd">
    <template id="sitemap_generate_error_email_template" label="Sitemap Generation Warnings" file="generate_warnings.html" type="text" module="Magento_Sitemap" area="adminhtml"/>
</config>