public function initializeBySitesAndConfigurations(array $sites, array $indexingConfigurationNames = ['*']): array
    {
        $initializationStatesBySiteId = [];
        foreach($sites as $site) {
            /** @var  Site $site */
            $initializationResult = $this->initializeBySiteAndIndexConfigurations($site, $indexingConfigurationNames);
            $initializationStatesBySiteId[$site->getRootPageId()] = $initializationResult;
        }

        return $initializationStatesBySiteId;
    }