code: public Observable<List<EventSubscriptionInner>> listByDomainTopicAsync(String resourceGroupName, String domainName, String topicName) {
          return listByDomainTopicWithServiceResponseAsync(resourceGroupName, domainName, topicName).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 domain topic.
  List all event subscriptions that have been created for a specific domain topic.
  
  @param resourceGroupName The name of the resource group within the user's subscription.
  @param domainName Name of the top level domain
  @param topicName Name of the domain topic
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the List&lt;EventSubscriptionInner&gt; object