code: public Observable<ServiceResponse<List<EventTypeInner>>> listEventTypesWithServiceResponseAsync(String topicTypeName) {
          if (topicTypeName == null) {
              throw new IllegalArgumentException("Parameter topicTypeName is required and cannot be null.");
          }
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          return service.listEventTypes(topicTypeName, this.client.apiVersion(), this.client.acceptLanguage(), this.client.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<List<EventTypeInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<List<EventTypeInner>>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<PageImpl<EventTypeInner>> result = listEventTypesDelegate(response);
                          List<EventTypeInner> items = null;
                          if (result.body() != null) {
                              items = result.body().items();
                          }
                          ServiceResponse<List<EventTypeInner>> clientResponse = new ServiceResponse<List<EventTypeInner>>(items, result.response());
                          return Observable.just(clientResponse);
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }
docs: List event types.
  List event types for a topic type.
  
  @param topicTypeName Name of the topic type
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the List&lt;EventTypeInner&gt; object