@Override
    public CompletableFuture<Void> quiesce() {
        if (!quiesced) {
            quiesced = true;

            if (numRunningTimers.get() == 0) {
                quiesceCompletedFuture.complete(null);
            }
        }

        return quiesceCompletedFuture;
    }
@Test
    void testQuiesceWhenNoRunningTimers() {
        ProcessingTimeServiceImpl processingTimeService =
                new ProcessingTimeServiceImpl(timerService, v -> v);
        assertThat(processingTimeService.quiesce()).isDone();
    }