code: public Observable<List<EventSubscriptionInner>> listRegionalBySubscriptionAsync(String location) {
          return listRegionalBySubscriptionWithServiceResponseAsync(location).map(new Func1<ServiceResponse<List<EventSubscriptionInner>>, List<EventSubscriptionInner>>() {
              @Override
              public List<EventSubscriptionInner> call(ServiceResponse<List<EventSubscriptionInner>> response) {
                  return response.body();
              }
          });
      }
docs: List all regional event subscriptions under an Azure subscription.
  List all event subscriptions from the given location under a specific Azure subscription.
  
  @param location Name of the location
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the List&lt;EventSubscriptionInner&gt; object