code: @Override
    public RetryDecision onUnavailable(
        @NonNull Request request,
        @NonNull ConsistencyLevel cl,
        int required,
        int alive,
        int retryCount) {
  
      RetryDecision decision = (retryCount == 0) ? RetryDecision.RETRY_NEXT : RetryDecision.RETHROW;
  
      if (decision == RetryDecision.RETRY_NEXT && LOG.isTraceEnabled()) {
        LOG.trace(RETRYING_ON_UNAVAILABLE, logPrefix, cl, required, alive, retryCount);
      }
  
      return decision;
    }
docs: {@inheritDoc}
  
  <p>This implementation triggers a maximum of one retry, to the next node in the query plan. The
  rationale is that the first coordinator might have been network-isolated from all other nodes
  (thinking they're down), but still able to communicate with the client; in that case, retrying
  on the same host has almost no chance of success, but moving to the next host might solve the
  issue.
  
  <p>Otherwise, the exception is rethrown.