code: public Observable<List<EventSubscriptionInner>> listByResourceAsync(String resourceGroupName, String providerNamespace, String resourceTypeName, String resourceName) {
          return listByResourceWithServiceResponseAsync(resourceGroupName, providerNamespace, resourceTypeName, resourceName).map(new Func1<ServiceResponse<List<EventSubscriptionInner>>, List<EventSubscriptionInner>>() {
              @Override
              public List<EventSubscriptionInner> call(ServiceResponse<List<EventSubscriptionInner>> response) {
                  return response.body();
              }
          });
      }
docs: List all event subscriptions for a specific topic.
  List all event subscriptions that have been created for a specific topic.
  
  @param resourceGroupName The name of the resource group within the user's subscription.
  @param providerNamespace Namespace of the provider of the topic
  @param resourceTypeName Name of the resource type
  @param resourceName Name of the resource
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the List&lt;EventSubscriptionInner&gt; object