public function getShadowLocales(ShadowLocaleBehavior $document)
    {
        $shadowLocales = [];
        $locales = $this->getLocales($document);
        $node = $this->getNode($document);
        foreach ($locales as $locale) {
            $shadowEnabledName = $this->encoder->localizedSystemName(
                ShadowLocaleSubscriber::SHADOW_ENABLED_FIELD,
                $locale
            );
            $shadowLocaleName = $this->encoder->localizedSystemName(
                ShadowLocaleSubscriber::SHADOW_LOCALE_FIELD,
                $locale
            );

            if ($node->getPropertyValueWithDefault($shadowEnabledName, false)) {
                $shadowLocales[$locale] = $node->getPropertyValue($shadowLocaleName);
            }
        }

        return $shadowLocales;
    }