public function getNote()
    {
        $message = null;

        if ($this->accept_mime_types !== null && $this->display_mime_types) {
            $displayable_types = $this->getDisplayableTypes();
            $message = new SwatMessage(
                sprintf(
                    Swat::ngettext(
                        'Valid files are the following type: %s.',
                        'Valid files are the following type(s): %s.',
                        count($displayable_types)
                    ),
                    implode(', ', $displayable_types)
                )
            );
        }

        return $message;
    }