PaginationDataSource.java

public class PaginationActivity extends AppCompatActivity {
    /**
     * Simulation of network data
     */
    private Single<List<String>> dataFromNetwork(final int page) {
        return Single.just(true)
                .delay(2, TimeUnit.SECONDS)
                .map(value -> {
                    List<String> items = new ArrayList<>();
                    for (int i = 1; i <= 10; i++) {
                        items.add("Item " + (page * 10 + i));
                    }
                    return items;
                });
    } 
}