code: public Observable<TopicSharedAccessKeysInner> listSharedAccessKeysAsync(String resourceGroupName, String topicName) {
          return listSharedAccessKeysWithServiceResponseAsync(resourceGroupName, topicName).map(new Func1<ServiceResponse<TopicSharedAccessKeysInner>, TopicSharedAccessKeysInner>() {
              @Override
              public TopicSharedAccessKeysInner call(ServiceResponse<TopicSharedAccessKeysInner> response) {
                  return response.body();
              }
          });
      }
docs: List keys for a topic.
  List the two keys used to publish to a topic.
  
  @param resourceGroupName The name of the resource group within the user's subscription.
  @param topicName Name of the topic
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the TopicSharedAccessKeysInner object