@Override
        protected ClickHouseNode get(ClickHouseNodes manager, ClickHouseNodeSelector t) {
            int size = manager.nodes.size();
            manager.index.set(size < 1 ? 0 : rand.nextInt(size));
            return super.get(manager, t);
        }
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