How can I get the stacktrace of a long running statement in a mutiny TimeOut

Question

I'm trying to get the stacktrace of the Thread.sleep in the following code snippet. Right now, the only stacktrace I'm getting is the one created by Mutiny upon timing out (which isn't helpful). I've tried following things:

• Catch any exception on the long running code, that's not triggered
• onCancellation is invoked but the thread stacktrace is the one from the TimeOut
• onTermination is invoked but the throwable is null
• onFailure after the timeout contains the stacktrace of the TimeOut

To give more context, in our case, we have a lot more going on which is long running and I can't pinpoint what exactly is causing the timeout. I would like to get the stacktrace of the long running code when the timeout happens so I know what needs to be fixed.

Uni.createFrom()
  .completionStage(CompletableFuture.supplyAsync(() -> {
      try {
          Thread.sleep(20000);
      } catch (Exception e) {
          e.printStackTrace(); //not triggered
      }
      return "item";
  }))
  .onCancellation().invoke(() ->{
      // stacktrace of timeout exception
  })
  .onTermination().invoke((s, throwable, aBoolean) -> {
      // throwable is NULL
  })
  .ifNoItem().after(Duration.ofMillis(100)).fail()
  .onFailure().invoke(ex -> {
      ex.printStackTrace(); //try to get the stacktrace of the Thread.sleep
  })
  .onFailure().recoverWithItem("error")
  .await().atMost(DEFAULT_TIMEOUT);
}

Thanks for assistance in advance!