public final ClickHouseNode getServer() {
        ClickHouseNode node = serverRef.get();
        if (node == null) {
            node = server.apply(getClient().getConfig().getNodeSelector());
            if (!serverRef.compareAndSet(null, node)) {
                node = serverRef.get();
            }
        }
        return node;
    }
Gets the server currently connected to. The initial value was determined by
the {@link java.util.function.Function} passed to constructor, and it may be
changed over time when failover is enabled.

@return non-null node
clickhouse-client/src/main/java/com/clickhouse/client/ClickHouseRequest.java