RxJavaでIntervalを設けつつのjustの使い方

Sample1.java

import io.reactivex.Flowable;
import java.util.concurrent.TimeUnit;

public class Sample1 {

    public static void main (String... args ) throws  Exception {
        Flowable<Integer> flowable1 = Flowable.just(1, 2, 3).map(s -> s * 2);
        Flowable<Long> flowable2 = Flowable.interval(1000, TimeUnit.MILLISECONDS);
        Flowable ziped = Flowable.zip(flowable1, flowable2, (f1, f2) ->f1);
        ziped.subscribe(System.out::println);
        Thread.sleep(5000L);
    }
}

もしかしてflowable2の方のintervalは終わらない？不安になったのでsubscribeでちゃんとFlowableSubscriberを実装して確認。
結論として問題なし。ちゃんとENDって表示されてる

import io.reactivex.Flowable;
import io.reactivex.FlowableSubscriber;
import org.reactivestreams.Subscription;

import java.util.concurrent.TimeUnit;

public class Sample1 {

    public static void main (String ... args ) throws  Exception {
        Flowable<Integer> flowable1 = Flowable.just(1, 2, 3).map(s -> s * 2);
        Flowable<Long> flowable2 = Flowable.interval(1000, TimeUnit.MILLISECONDS);
        Flowable<Integer> ziped = Flowable.zip(flowable1, flowable2, (f1, f2) ->f1);
        ziped.subscribe(new FlowableSubscriber<Integer>() {
            private Subscription subscription;
            @Override
            public void onSubscribe(Subscription s) {
                subscription = s;
                s.request(1L);
            }

            @Override
            public void onNext(Integer o) {
                System.out.println(o);
                subscription.request(1L);
            }

            @Override
            public void onError(Throwable t) {

            }

            @Override
            public void onComplete() {
                System.out.println("END");
            }
        });
        Thread.sleep(5000L);
    }
}