presto-elasticsearch/src/main/java/io/prestosql/elasticsearch/client/ElasticsearchClient.java/ElasticsearchClient/initialize
class ElasticsearchClient:    @PostConstruct
    public void initialize()
    {
        if (!started.getAndSet(true)) {
            // do the first refresh eagerly
            refreshNodes();

            executor.scheduleWithFixedDelay(this::refreshNodes, refreshInterval.toMillis(), refreshInterval.toMillis(), TimeUnit.MILLISECONDS);
        }
    }