@Override
        protected ScheduledExecutorService getScheduler() {
            return null;
        }
Load balancing policy. In general, a policy is responsible for 3 things: 1)
get node from a managed list; 2) managing node's status; and 3) optionally
schedule background tasks like node discovery and health check.
clickhouse-client/src/main/java/com/clickhouse/client/ClickHouseLoadBalancingPolicy.java