docs: @Nonnull
    private DruidConnection getDruidConnection(final String connectionId)
    {
      final DruidConnection connection = connections.get(connectionId);
  
      if (connection == null) {
        throw new NoSuchConnectionException(connectionId);
      }
  
      return connection.sync(
          exec.schedule(
              () -> {
                log.debug("Connection[%s] timed out.", connectionId);
                closeConnection(new ConnectionHandle(connectionId));
              },
              new Interval(DateTimes.nowUtc(), config.getConnectionIdleTimeout()).toDurationMillis(),
              TimeUnit.MILLISECONDS
          )
      );
    }