java如何将代码转换为CompletableFuture？

Question

我以前有一个可调用的类

class SampleTask implements Callable<Double> {
  @Override
  public Double call() throws Exception {
    return 0d;
  }
}

我曾经用ExecutorService来提交Callable。如何更改为使用CompletableFuture.supplyAsync

以下代码无法编译

SampleTask task = new SampleTask();
CompletableFuture.supplyAsync(task);

No instance of type of variable U exists so that SampleTask conforms to Supplier