public static ClickHouseDnsResolver getInstance() {
        return instance;
    }
Default DNS resolver. It tries to look up service record (SRV record) when
{@link com.clickhouse.client.config.ClickHouseDefaults#SRV_RESOLVE} is set to
{@code true}.
clickhouse-client/src/main/java/com/clickhouse/client/ClickHouseDnsResolver.java