Please add setHtmlAttribute() or addClass to addExportCallback button

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!

Start by locating the addExportCallback entry point and the button object it returns. Check how that object currently handles classes and HTML attributes, then verify that the requested class or attribute can be applied to the generated export button; no test file is named in the issue.