public static function addBreadcrumbList()
    {
        $view = Yii::$app->getView();

        $breadcrumbList = [];
        if (isset($view->params['breadcrumbs'])) {
            $position = 1;
            foreach ($view->params['breadcrumbs'] as $breadcrumb) {
                if (is_array($breadcrumb)) {
                    $breadcrumbList[] = (object)[
                        "@type" => "http://schema.org/ListItem",
                        "http://schema.org/position" => $position,
                        "http://schema.org/item" => (object)[
                            "@id" => Url::to($breadcrumb['url'], true),
                            "http://schema.org/name" => $breadcrumb['label'],
                        ]
                    ];
                } else {
                    // Is it ok to omit URL here or not? Google is not clear on that:
                    // http://stackoverflow.com/questions/33688608/how-to-markup-the-last-non-linking-item-in-breadcrumbs-list-using-json-ld
                    $breadcrumbList[] = (object)[
                        "@type" => "http://schema.org/ListItem",
                        "http://schema.org/position" => $position,
                        "http://schema.org/item" => (object)[
                            "http://schema.org/name" => $breadcrumb,
                        ]
                    ];
                }
                $position++;
            }
        }

        $doc = (object)[
            "@type" => "http://schema.org/BreadcrumbList",
            "http://schema.org/itemListElement" => $breadcrumbList
        ];

        JsonLDHelper::add($doc);
    }