RestartSource.onFailuresWithBackoff does not work with AlpakkaS3Client.listBucket as expected

Hi, i would like to restart on failures a call that does an s3 listing (akka-stream v2.5.31 and alpkakka v2.0.0):

        minBackoff   = 3 seconds,
        maxBackoff   = 3 seconds,
        randomFactor = 0,
        maxRestarts  = 3
      ) { () =>
          .listBucket("myBucket", None)
          .map { _ =>
  "Listing ok -> ")

But doesn’t work accordingly to backOff properties, my s3 server is not running, so i expect the call to be retried 3 times, but the call fails with a without retries :

server 16:34:15.075 [] WARN  a.s.s.RestartWithBackoffSource -  Restarting graph due to failure. stack_trace:  ( Tcp command [Connect(localhost:4572,None,List(),Some(10 seconds),true)] failed because of Connection refused)

I am i missing something ?

Ok, in fact it works but the timeout is so long that it looks like it not doing anything …