@Test(timeout = 5_000)
public void testLongAsynchronousAction() {

    List<String> result = new CopyOnWriteArrayList<>();
    for (int i = 0; i < 5; i++) {
        int index = i;
        reactorSerializedInvoker.submit(Mono.delay(Duration.ofMillis(10)).map(tick -> "#" + index)).subscribe(result::add);
    }
    await().until(() -> result.size() == 5);
    assertThat(result).contains("#0", "#1", "#2", "#3", "#4");
}