server-tools/base_exports_manager/static/src/xml/base.xml

<?xml version="1.0" encoding="UTF-8"?>
<templates id="template" xml:space="preserve">

<t t-extend="ExportTreeView-Secondary.children">
    <t t-jquery="#tree-column a" t-operation="append">
         (<t t-esc="field.id"/>)
    </t>
</t>

</templates>