Что выведет: цепочка CompletableFuture

import java.util.concurrent.*;

public class Main {
    public static void main(String[] args) {
        CompletableFuture<Integer> a = CompletableFuture.supplyAsync(() -> 10);
        CompletableFuture<Integer> b = CompletableFuture.supplyAsync(() -> 5);
        int sum = a.thenCombine(b, Integer::sum).thenApply(x -> x * 2).join();
        System.out.println(sum);

        String r = CompletableFuture.supplyAsync(() -> {
                if (true) throw new IllegalStateException("bad");
                return "ok";
            })
            .thenApply(s -> s + "!")
            .exceptionally(e -> "recovered: " + e.getCause().getMessage())
            .join();
        System.out.println(r);

        CompletableFuture<String> c = CompletableFuture.supplyAsync(() -> "x")
            .thenCompose(s -> CompletableFuture.supplyAsync(() -> s + "y"));
        System.out.println(c.join());
    }
}