server-tools/base_custom_info/demo/defaults.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2016 Jairo Llopis <jairo.llopis@tecnativa.com>
     License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl). -->

<odoo>

    <record id="prop_weaknesses" model="custom.info.property">
        <field name="default_value">Huge glasses</field>
    </record>

</odoo>