code: private boolean retryCurrentRoute() {
      return transmitter.connection != null
          && transmitter.connection.routeFailureCount == 0
          && Util.sameConnection(transmitter.connection.route().address().url(), address.url());
    }
docs: Return true if the route used for the current connection should be retried, even if the
  connection itself is unhealthy. The biggest gotcha here is that we shouldn't reuse routes from
  coalesced connections.