Github user zentol commented on the issue:
https://github.com/apache/flink/pull/4802
The reason why i went for the CompletableFuture route is to stay closes to
the current code. The CliFrontend is waiting the the response and prints
"Waiting...", which we can't do when doing the call synchronously since the
ClusterClient shouldn't print anything.
That said, i do like making them asynchronous in general.---
