How to fill the grouped heading row of Analytical table with icon / button

Question

I have one Analytical table under my smart table as follow;

 <st:SmartTable
id="idCompanyTable"
tableType="AnalyticalTable"
entitySet="--">
<table:AnalyticalTable ----- >

    <table:AnalyticalColumn id="idColumnLinkToOS">
        <Text id="--" text="OS"/>
        <table:template>          
            <Button id="id--"  type="Transparent" icon="sap-icon://org-chart" press="." />
        </table:template>

        <table:customData>
            <core:CustomData
                key="p13nData"
                value='\{"columnKey":"Test", "columnIndex":"8"}'
            />
        </table:customData>
    </table:AnalyticalColumn>
</table:AnalyticalTable>

</st:SmartTable>

The table is grouped by first column as;

oSmartTable.applyVariant({
                group: {
                    groupItems: [{
                        columnKey: "SystemIdWithClient",
                        operation: "GroupAscending",
                        showIfGrouped: true
                    }]
                }
            });

BUT the table is showing the desired button / icon only on the expanded rows; So i want to display that button / icon also on the grouped heading AS: