public static function delete_feedback_for_grade(assign_plugin_request_data $requestdata) {
        global $DB;

        $fs = new \file_storage();
        $fs->delete_area_files($requestdata->get_context()->id, ASSIGNFEEDBACK_COMMENTS_COMPONENT,
            ASSIGNFEEDBACK_COMMENTS_FILEAREA, $requestdata->get_pluginobject()->id);

        $DB->delete_records('assignfeedback_comments', ['assignment' => $requestdata->get_assignid(),
                'grade' => $requestdata->get_pluginobject()->id]);
    }