Final Class Yiisoft\Yii\Swagger\Formatter\ParamsFormatter

                public function format(array $params): string
{
    if (ArrayHelper::isAssociative($params)) {
        $keys = array_keys($params);
        $result = [];
        foreach ($keys as $key) {
            $element = Html::encode($key) . ':';
            if (is_array($params[$key])) {
                $result[] = $element . $this->format($params[$key]);
                continue;
            }
            $result[] = $element . '"' . Html::encode((string) $params[$key]) . '"';
        }
        return '{' . implode(', ', $result) . '}';
    }
    $result = array_map(Html::encode(...), $params);
    return '[' . implode(', ', $result) . ']';
}