@Override
    public Publisher<Void> close() {
        try {
            client.close();
            closed = true;
            return Mono.empty();
        } catch (Exception e) {
            return Mono.error(e);
        }
    }
Transactions are not supported so this is a no-op implementation,
clickhouse-r2dbc/src/main/java/com/clickhouse/r2dbc/connection/ClickHouseConnection.java