public final class CompletableFutures {

    public static <T> CompletableFuture<List<T>> sequence(List<CompletableFuture<T>> futures) {
        CompletableFuture<Void> allDone = CompletableFuture.allOf(futures.toArray(new CompletableFuture[futures.size()]));
        return allDone.thenApply(v -> futures.stream().map(future -> future.join()).collect(toList()));
    }

}