code: public final void deleteTopic(ProjectTopicName topic) {
  
      DeleteTopicRequest request =
          DeleteTopicRequest.newBuilder().setTopic(topic == null ? null : topic.toString()).build();
      deleteTopic(request);
    }
docs: Deletes the topic with the given name. Returns `NOT_FOUND` if the topic does not exist. After a
  topic is deleted, a new topic may be created with the same name; this is an entirely new topic
  with none of the old configuration or subscriptions. Existing subscriptions to this topic are
  not deleted, but their `topic` field is set to `_deleted-topic_`.
  
  <p>Sample code:
  
  <pre><code>
  try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
  ProjectTopicName topic = ProjectTopicName.of("[PROJECT]", "[TOPIC]");
  topicAdminClient.deleteTopic(topic);
  }
  </code></pre>
  
  @param topic Name of the topic to delete. Format is `projects/{project}/topics/{topic}`.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails