code: public Observable<Page<SiteInner>> listWebAppsNextAsync(final String nextPageLink) {
          return listWebAppsNextWithServiceResponseAsync(nextPageLink)
              .map(new Func1<ServiceResponse<Page<SiteInner>>, Page<SiteInner>>() {
                  @Override
                  public Page<SiteInner> call(ServiceResponse<Page<SiteInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Get all apps associated with an App Service plan.
  Get all apps associated with an App Service plan.
  
  @param nextPageLink The NextLink from the previous successful call to List operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;SiteInner&gt; object