rxjava2合并可观测数据没有停止

为什么? merge 之后操作员未停止 obs2 未完成?我正在看这本书的图表

"Reactive Programming on Android with RxJava"

从我的观点来看,如果任何合并的观测值 onCompleted ,则另一个可观察对象也终止(完成)。

但事实并非如此。为什么呢?

这是我的密码。obs1应该在obs2之后终止,但是它是无止境的

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = findViewById(R.id.btn);

        Observable.merge(obs1, obs2)
                .subscribe(data -> Log.d(TAG, String.valueOf(data)));
    }

    Observable<String> obs1 = Observable.interval(1, TimeUnit.SECONDS)
            .map(data -> "obs1: " + data);

    Observable obs2 =
            Observable.just(1, 2, 3, 4, 5)
                    .delay(1, TimeUnit.SECONDS)
                    .filter(data -> data < 5)
                    .map(data -> "obs2: " + data)
                    .doOnComplete(() -> Log.d(TAG, "done"));

D/MainActivity: obs1: 0
                obs2: 1
                obs2: 2
                obs2: 3
D/MainActivity: obs2: 4
                done
D/MainActivity: obs1: 1
D/MainActivity: obs1: 2
D/MainActivity: obs1: 3
D/MainActivity: obs1: 4
D/MainActivity: obs1: 5
D/MainActivity: obs1: 6