Please add setHtmlAttribute() or addClass to addExportCallback button

[BigOHenry]

Please add ->setHtmlAttribute() or ->addClass() to addExportCallback button. When i want to add disabled class to button, i must do this:

$disabled_class = 'btn btn-xs btn-default';

        if ($grid->getDataSource()->getCount() == 0) {
            $disabled_class = 'btn btn-xs btn-default disabled';
        }

        $grid->addExportCallback(....)->setClass($disabled_class);

// much better way:
$grid->addExportCallback(....)->addClass($disabled_class);

Thank you very much!