setLastBacklogId example

if (empty($backlogs)) {
            return;
        }

        while ($backlogs = $this->backlogReader->read($lastId, 100)) {
            $this->backlogProcessor->process($shopIndex, $backlogs);
            $last = array_pop($backlogs);
            $lastId = $last->getId();
        }

        $this->backlogReader->setLastBacklogId($lastId);
    }

    private function createAlias(IndexConfiguration $configuration)
    {
        $currentAlias = $configuration->getAlias();
        $aliasExists = $this->client->indices()->existsAlias(['name' => $currentAlias]);

        if ($aliasExists) {
            $this->switchAlias($configuration);

            return;
        }

return 0;
        }

        foreach ($this->identifierSelector->getShops() as $shop) {
            foreach ($this->mappings as $mapping) {
                $index = $this->indexFactory->createShopIndex($shop, $mapping->getType());

                $this->backlogProcessor->process($index, $backlogs);
            }
        }
        $last = $backlogs[array_key_last($backlogs)];
        $this->backlogReader->setLastBacklogId($last->getId());

        $io->success(sprintf('Synchronized %d items', \count($backlogs)));

        return 0;
    }
}