CountDownLatch isInterruptibleRegistered = new CountDownLatch(1);
    SlowChannel slowChannel = new SlowChannel();
    InterruptibleTask<@Nullable Void> task =
        new InterruptibleTask<@Nullable Void>() {
          @Override
          @Nullable Void runInterruptibly() throws Exception {
            slowChannel.doBegin();
            isInterruptibleRegistered.countDown();
            try {