docs: public Policy getTopicPolicy(String topicId) throws Exception {
      // [START pubsub_get_topic_policy]
      try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
        ProjectTopicName topicName = ProjectTopicName.of(projectId, topicId);
        Policy policy = topicAdminClient.getIamPolicy(topicName.toString());
        if (policy == null) {
          // topic iam policy was not found
        }
        return policy;
      }
      // [END pubsub_get_topic_policy]
    }