public function upgrade(context $oldcontext,
                            stdClass $oldassignment,
                            stdClass $oldsubmission,
                            stdClass $grade,
                            & $log) {
        global $DB;

        $feedbackcomments = new stdClass();
        $feedbackcomments->commenttext = $oldsubmission->submissioncomment;
        $feedbackcomments->commentformat = FORMAT_HTML;

        $feedbackcomments->grade = $grade->id;
        $feedbackcomments->assignment = $this->assignment->get_instance()->id;
        if (!$DB->insert_record('assignfeedback_comments', $feedbackcomments) > 0) {
            $log .= get_string('couldnotconvertgrade', 'mod_assign', $grade->userid);
            return false;
        }

        return true;
    }