code: public Observable<Page<EventSubscriptionInner>> listAsync() {
          return listWithServiceResponseAsync().map(new Func1<ServiceResponse<List<EventSubscriptionInner>>, Page<EventSubscriptionInner>>() {
              @Override
              public Page<EventSubscriptionInner> call(ServiceResponse<List<EventSubscriptionInner>> response) {
                  PageImpl<EventSubscriptionInner> page = new PageImpl<>();
                  page.setItems(response.body());
                  return page;
              }
          });
      }
docs: Get an aggregated list of all global event subscriptions under an Azure subscription.
  List all aggregated global event subscriptions under a specific Azure subscription.
  
  @return the observable to the List&lt;EventSubscriptionInner&gt; object