Add declarative API to keep track of the checked buttons in a non-exclusive ButtonGroup

I need to enable a "Confirm" button if there is at least one checked AbstractButton in a ListView. Currently my best option is to listen to ButtonGroup's clicked() signal and manage the number of checked items myself. It would be nice if there was a property that I could bind to instead:

Button {
     enabled: buttonGroup.checkedButtons.length > 0
}