docs: public Observable<Page<SubscriptionUsageInner>> listByLocationNextAsync(final String nextPageLink) {
          return listByLocationNextWithServiceResponseAsync(nextPageLink)
              .map(new Func1<ServiceResponse<Page<SubscriptionUsageInner>>, Page<SubscriptionUsageInner>>() {
                  @Override
                  public Page<SubscriptionUsageInner> call(ServiceResponse<Page<SubscriptionUsageInner>> response) {
                      return response.body();
                  }
              });
      }