code: public Observable<ServiceResponse<Page<PolicySetDefinitionInner>>> listBuiltInSinglePageAsync() {
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          return service.listBuiltIn(this.client.apiVersion(), this.client.acceptLanguage(), this.client.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<Page<PolicySetDefinitionInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<PolicySetDefinitionInner>>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<PageImpl<PolicySetDefinitionInner>> result = listBuiltInDelegate(response);
                          return Observable.just(new ServiceResponse<Page<PolicySetDefinitionInner>>(result.body(), result.response()));
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }
docs: Retrieves built-in policy set definitions.
  This operation retrieves a list of all the built-in policy set definitions.
  
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the PagedList&lt;PolicySetDefinitionInner&gt; object wrapped in {@link ServiceResponse} if successful.