Противодействие RxJava и количество обращений к производителю

Я пытаюсь создать бесконечную прокрутку в своем приложении для Android, используя обратное давление в rx Java. Я хочу, чтобы он вызывал внешнюю службу только запрошенное количество раз (после вызова request(1)). Но после использования плоской карты каждый subscribe загружает 16 страниц.

ниже моего кода с ожидаемыми результатами. Почти каждый тест не проходит из-за первого запроса (при n=16)

import org.junit.Before;
import org.junit.Test;
import org.mockito.Mockito;
import rx.Observable;
import rx.observers.TestSubscriber;

import java.util.Arrays;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

import static java.util.Collections.emptyList;
import static org.mockito.Mockito.*;
import static rx.internal.util.UtilityFunctions.identity;

public class ServiceObservablesTest {


    public static <T> Observable<List<T>> create(DataProvider<T> dataProvider) {
        Observable<Observable<List<T>>> metaObservalble = Observable.create(subscriber -> {
            AtomicInteger pageNumber = new AtomicInteger();
            subscriber.setProducer(n -> {
                // at subscribe rxJava makes request for 16 elements - probably because of flatMap
                // after first request with 16 elements everything seems to work fine even if i ignore the 'n' param

                Observable<List<T>> page = dataProvider.requestPage(pageNumber.getAndIncrement());
                subscriber.onNext(page);

            });
        });
        return metaObservalble.flatMap(identity()).takeWhile(page -> !page.isEmpty());
    }

    public interface DataProvider<T> {
        Observable<List<T>> requestPage(int page);
    }


    private DataProvider provider;

    @Before
    public void setUp() throws Exception {
        provider = Mockito.mock(DataProvider.class);
        List<Object> list = Arrays.asList(new Object());
        when(provider.requestPage(anyInt())).thenReturn(Observable.just(list));
    }

    @Test
    public void shouldRequestOnlyFirstPageOnSubscribe() {
        //given

        TestSubscriber<List<Object>> subscriber = new TestSubscriber<>(1);
        Observable<List<Object>> flightsObservable = create(provider);

        //when
        flightsObservable.subscribe(subscriber);

        //then
        subscriber.assertValueCount(1);
        subscriber.assertNotCompleted();

        verify(provider, times(1)).requestPage(0);
        verify(provider, never()).requestPage(1);
    }


    @Test
    public void shouldRequestNumberOfPagesSpecified() {
        //given

        int requested_pages = 5;
        TestSubscriber<List<Object>> subscriber = new TestSubscriber<>(0);
        Observable<List<Object>> flightsObservable = create(provider);

        //when
        flightsObservable.subscribe(subscriber);
        subscriber.requestMore(requested_pages);

        //then
        subscriber.assertValueCount(requested_pages);
        subscriber.assertNotCompleted();


        for (int i = 0; i < requested_pages; i++) {
            verify(provider, times(1)).requestPage(i);
        }
        verify(provider, never()).requestPage(requested_pages);

    }


    @Test
    public void shouldCompleteAfterRetrievingEmptyResult() {
        //given

        int emptyPage = 2;
        when(provider.requestPage(emptyPage)).thenReturn(Observable.just(emptyList()));

        TestSubscriber<List<Object>> subscriber = new TestSubscriber<>(100);
        Observable<List<Object>> flightsObservable = create(provider);


        //when
        flightsObservable.subscribe(subscriber);

        //then
        subscriber.assertValueCount(emptyPage);
        subscriber.assertCompleted();


        verify(provider, times(1)).requestPage(0); //requested at subscribe
        for (int i = 1; i <= emptyPage; i++) {
            verify(provider, times(1)).requestPage(i);
        }
        verify(provider, never()).requestPage(emptyPage + 1);

    }

    @Test
    public void shouldRequestNextPageWhenRequestedMore() {
        //given

        TestSubscriber<List<Object>> subscriber = new TestSubscriber<>(1);
        Observable<List<Object>> flightsObservable = create(provider);

        //when
        flightsObservable.subscribe(subscriber);
        subscriber.requestMore(1);

        //then
        subscriber.assertValueCount(2);
        verify(provider, times(1)).requestPage(0);
        verify(provider, times(1)).requestPage(1);
        verify(provider, never()).requestPage(2);

        //when
        subscriber.requestMore(1);

        //then
        subscriber.assertValueCount(3);
        subscriber.assertNotCompleted();

        verify(provider, times(1)).requestPage(0);
        verify(provider, times(1)).requestPage(1);
        verify(provider, times(1)).requestPage(2);
        verify(provider, never()).requestPage(3);

    }

    @Test
    public void shouldWorkWithMultipleSubscribers() {

        //given

        TestSubscriber<List<Object>> subscriber1 = new TestSubscriber<>(1);
        TestSubscriber<List<Object>> subscriber2 = new TestSubscriber<>(1);
        Observable<List<Object>> flightsObservable = create(provider);

        //when
        flightsObservable.subscribe(subscriber1);
        flightsObservable.subscribe(subscriber2);

        //then
        subscriber1.assertValueCount(1);
        subscriber2.assertValueCount(1);

        verify(provider, times(2)).requestPage(0);
        verify(provider, never()).requestPage(1);

        //when
        subscriber1.requestMore(1);
        //then
        subscriber1.assertValueCount(2);
        subscriber2.assertValueCount(1);

        verify(provider, times(2)).requestPage(0);
        verify(provider, times(1)).requestPage(1);
        verify(provider, never()).requestPage(2);

        //when
        subscriber2.requestMore(1);
        //then
        subscriber1.assertValueCount(2);
        subscriber2.assertValueCount(2);

        verify(provider, times(2)).requestPage(0);
        verify(provider, times(2)).requestPage(1);
        verify(provider, never()).requestPage(2);
    }

}