Github user tillrohrmann commented on the issue:
https://github.com/apache/flink/pull/4802
I'm not entirely sure whether this "Waiting..." is consistent. The current
`list` implementation does not do it. Moreover, so far all `ClusterClient`
operations are synchronous (e.g. `stop` and `cancel`). In general I don't have
strong feelings about returning a future or the result, but so far I think we
always made the call synchronous and, thus, diverge from it with this change.---
