docs: public ListTopicsPagedResponse listTopics() throws Exception {
      // [START pubsub_list_topics]
      try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
        ListTopicsRequest listTopicsRequest =
            ListTopicsRequest.newBuilder().setProject(ProjectName.format(projectId)).build();
        ListTopicsPagedResponse response = topicAdminClient.listTopics(listTopicsRequest);
        Iterable<Topic> topics = response.iterateAll();
        for (Topic topic : topics) {
          // do something with the topic
        }
        return response;
      }
      // [END pubsub_list_topics]
    }