Fetch restaurants with their Yelp rating and review count

RestaurantDataSource.java

public Single<Pair<List<Restaurant>, Boolean>> getRestaurantList(int userId) {
    Single<List<Restaurant>> restaurantListSingle = 
            ddApi.getUserInfo(userId).flatMap(user -> {
                return ddApi.getAvailableRestaurant(user.defaultAddress.lat, user.defaultAddress.lng);
            });

    Single<Boolean> showPhotoExperimentSingle = 
            ddApi.getShowPhotosExperiment(userId);

    return restaurantListSingle.zipWith(showPhotoExperimentSingle, Pair::new);
}