web/web_dom_model_classes/static/src/xml/web_widget_classes.xml

<?xml version="1.0" encoding="UTF-8"?>
<templates id="template">
    <t t-extend="ViewManagerAction">
        <t t-jquery="div:first">
            this.attr('t-att-class', '"' + this.attr('class') + ' oe_model_" + (widget.dataset.model.replace(new RegExp("\\\\.","g"), "_"))');
            this.attr('class', null);
        </t>
    </t>
</templates>