yii\filters\Cors::headerize PHP Метод

    protected function headerize($string)
    {
        $headers = preg_split("/[\\s,]+/", $string, -1, PREG_SPLIT_NO_EMPTY);
        $headers = array_map(function ($element) {
            return str_replace(' ', '-', ucwords(strtolower(str_replace(['_', '-'], [' ', ' '], $element))));
        }, $headers);
        return implode(', ', $headers);
    }