public static function toResults(array $items) {

        $output = [];

        foreach ($items as $current) {

            if (false === ($current instanceof Select2ItemInterface)) {
                throw new InvalidArgumentException("The item must implements Select2ItemInterface");
            }

            $output[] = [
                "id"   => $current->getSelect2ItemId(),
                "text" => $current->getSelect2ItemText(),
            ];
        }

        return $output;
    }