code: @Deprecated
      public static <V> CompletableFuture<V> failedFuture(Throwable throwable)
      {
          requireNonNull(throwable, "throwable is null");
          CompletableFuture<V> future = new CompletableFuture<>();
          future.completeExceptionally(throwable);
          return future;
      }
docs: Returns a failed future containing the specified throwable.