static boolean isReady(@Nullable CompletableFuture<?> future) {
    return (future != null) && future.isDone()
        && !future.isCompletedExceptionally()
        && (future.join() != null);
  }
@Test(dataProvider = "successful")
  public void isReady_success(CompletableFuture<Integer> future) {
    assertThat(Async.isReady(future)).isTrue();
  }