protected function delete_feedback_files() {
        // We only support feedback files for modules atm.
        if ($this->grade_item && $this->grade_item->is_external_item()) {
            $context = $this->get_context();

            $fs = new file_storage();
            $fs->delete_area_files($context->id, GRADE_FILE_COMPONENT, GRADE_FEEDBACK_FILEAREA, $this->id);

            // Grade history only gets deleted when we delete the whole grade item.
        }

        return true;
    }