server-ux/barcode_action/views/barcode_templates.xml

<?xml version="1.0" encoding="UTF-8" ?>
<odoo>
    <template id="assets_backend" name="pos_validation_barcode assets"
              inherit_id="web.assets_backend">
        <xpath expr="." position="inside">
            <script type="text/javascript"
                    src="/barcode_action/static/src/js/action_barcode_form.js"/>
            <script type="text/javascript"
                    src="/barcode_action/static/src/js/action_barcode_widget.js"/>
        </xpath>
    </template>
</odoo>