code: public Observable<ServiceResponse<Page<RecommendationInner>>> listHistoryForWebAppSinglePageAsync(final String resourceGroupName, final String siteName, final String filter) {
          if (resourceGroupName == null) {
              throw new IllegalArgumentException("Parameter resourceGroupName is required and cannot be null.");
          }
          if (siteName == null) {
              throw new IllegalArgumentException("Parameter siteName is required and cannot be null.");
          }
          if (this.client.subscriptionId() == null) {
              throw new IllegalArgumentException("Parameter this.client.subscriptionId() is required and cannot be null.");
          }
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          return service.listHistoryForWebApp(resourceGroupName, siteName, this.client.subscriptionId(), filter, this.client.apiVersion(), this.client.acceptLanguage(), this.client.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<Page<RecommendationInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<RecommendationInner>>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<PageImpl<RecommendationInner>> result = listHistoryForWebAppDelegate(response);
                          return Observable.just(new ServiceResponse<Page<RecommendationInner>>(result.body(), result.response()));
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }
docs: Get past recommendations for an app, optionally specified by the time range.
  Get past recommendations for an app, optionally specified by the time range.
  
  ServiceResponse<PageImpl<RecommendationInner>> * @param resourceGroupName Name of the resource group to which the resource belongs.
  ServiceResponse<PageImpl<RecommendationInner>> * @param siteName Name of the app.
  ServiceResponse<PageImpl<RecommendationInner>> * @param filter Filter is specified by using OData syntax. Example: $filter=channels eq 'Api' or channel eq 'Notification' and startTime eq '2014-01-01T00:00:00Z' and endTime eq '2014-12-31T23:59:59Z' and timeGrain eq duration'[PT1H|PT1M|P1D]
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the PagedList&lt;RecommendationInner&gt; object wrapped in {@link ServiceResponse} if successful.