yii\web\Link::serialize PHP Method

    public static function serialize(array $links)
    {
        foreach ($links as $rel => $link) {
            if (is_array($link)) {
                foreach ($link as $i => $l) {
                    $link[$i] = $l instanceof self ? array_filter((array) $l) : ['href' => $l];
                }
                $links[$rel] = $link;
            } elseif (!$link instanceof self) {
                $links[$rel] = ['href' => $link];
            }
        }
        return $links;
    }

 /**
  * Serializes a pagination into an array.
  * @param Pagination $pagination
  * @return array the array representation of the pagination
  * @see addPaginationHeaders()
  */
 protected function serializePagination($pagination)
 {
     return ['_links' => Link::serialize($pagination->getLinks(true)), '_meta' => ['totalCount' => $pagination->totalCount, 'pageCount' => $pagination->getPageCount(), 'currentPage' => $pagination->getPage(), 'perPage' => $pagination->getPageSize()]];
 }