I have this in xml:

    record id="inokap_product_template_search_view" model="ir.ui.view"
        field name="name"> product.template.search /field
        field name="model"> product.template /field
        field name="inherit_id" ref="product.product_template_search_view"/
        field name="priority" eval="16"/
        field name="arch" type="xml"
            search
                group expand="1" string="Group By"
                    filter string="Article spécial" name="group_product_type" domain="[]" context="{'group_by': 'product_type', 'search_default_group_product_type': True}"/
                    filter name="cam" string="CAM" domain="[('product_type', '=', 'camera')]" context="{'product_type': 'camera', 'search_default_product_type_camera': 1}"/
                /group
            /search
        /field
    /record

I already add search_default_ but it doesn't work, or even I try with this:

'search_default_group_product_type': 0

I also already tried to add for the action like this:

    record id="action_product_template_tree" model="ir.actions.act_window"
        field name="name" Product Template Tree /field
        field name="res_model" product.template /field
        field name="view_mode" tree,form /field
        field name="view_id" ref="product.product_template_tree_view"/
        field name="context" {'search_default_group_product_type': True} /field>
    /record