public static function getProperties()
    {
        return [
            'AttachmentID' => [false, self::PROPERTY_TYPE_STRING, null, false, false],
            'FileName' => [true, self::PROPERTY_TYPE_STRING, null, false, false],
            'Url' => [false, self::PROPERTY_TYPE_STRING, null, false, false],
            'MimeType' => [false, self::PROPERTY_TYPE_STRING, null, false, false],
            'ContentLength' => [false, self::PROPERTY_TYPE_INT, null, false, false],
        ];
    }