publishsubject + flatmap problem

other publishsubject

List<ChatChooseItem> chatChooseItems = getMockItems();

List<ChatChooseItem> testList = new ArrayList<>();
PublishSubject<String> publishSubject = PublishSubject.create();
publishSubject
        .throttleWithTimeout(300, TimeUnit.MILLISECONDS)
        .flatMap(s -> Observable.from(chatChooseItems)
                .filter(chatChooseItem -> chatChooseItem.getName().toLowerCase().contains(s.toLowerCase()))
                .toSortedList((lhs, rhs) -> lhs.getName().toLowerCase().compareTo(rhs.getName().toLowerCase()))
        )
        .subscribe(testList::addAll);

publishSubject.onNext("he");

Awaitility.await().until(() -> testList.size() > 0);

MatcherAssert.assertThat(testList.size(), CoreMatchers.is(IsEqual.equalTo(2)));

publishsubject

List<ChatChooseItem> chatChooseItems = getMockItems();

List<ChatChooseItem> testList = new ArrayList<>();
PublishSubject<String> publishSubject = PublishSubject.create();
publishSubject
        .throttleWithTimeout(300, TimeUnit.MILLISECONDS)
        .flatMap(s -> Observable.from(chatChooseItems)
                .filter(chatChooseItem -> chatChooseItem.getName().toLowerCase()
                        .contains(s.toLowerCase())))
        .toSortedList((lhs, rhs) -> lhs.getName().toLowerCase().compareTo(rhs.getName().toLowerCase()))
        .subscribe(testList::addAll);

publishSubject.onNext("he");

Awaitility.await().until(() -> testList.size() > 0);

MatcherAssert.assertThat(testList.size(), CoreMatchers.is(IsNull.notNullValue()));