private function reindex($productIds)
    {
        $this->indexerRegistry->get(\Magento\CatalogSearch\Model\Indexer\Fulltext::INDEXER_ID)->reindexList($productIds);
    }
private function reindex($productIds)
    {
        $this->indexerRegistry->get(\Magento\CatalogSearch\Model\Indexer\Fulltext::INDEXER_ID)->reindexList($productIds);
    }
private function reindex ( $ productIds ) { $ this -> indexerRegistry -> get ( \ Magento \ CatalogSearch \ Model \ Indexer \ Fulltext :: INDEXER_ID ) -> reindexList ( $ productIds ) ; }
Reindex product on position change.

@param array $productIds Product ids to be reindexed.

@return void
Reindex product on position change .