code: public Observable<TopicInner> beginCreateOrUpdateAsync(String resourceGroupName, String topicName, TopicInner topicInfo) {
          return beginCreateOrUpdateWithServiceResponseAsync(resourceGroupName, topicName, topicInfo).map(new Func1<ServiceResponse<TopicInner>, TopicInner>() {
              @Override
              public TopicInner call(ServiceResponse<TopicInner> response) {
                  return response.body();
              }
          });
      }
docs: Create a topic.
  Asynchronously creates a new topic with the specified parameters.
  
  @param resourceGroupName The name of the resource group within the user's subscription.
  @param topicName Name of the topic
  @param topicInfo Topic information
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the TopicInner object