<?xml version="1.0"?>
<data><list position="attributes">
                <attribute name="default_group_by"/>
            </list>
            <field name="user_ids" position="attributes">
                <attribute name="invisible">1</attribute>
            </field>
            <field name="user_ids" position="after">
                <field name="portal_user_names" string="Assignees" optional="show"/>
            </field>
            
        </data>