public void ListTopics()
    {
        // <ListTopics>
        PublisherClient client = PublisherClient.Create();

        // Alternative: use a known project resource name:
        // projects/{PROJECT_ID}
        string projectName = PublisherClient.GetProjectName("PROJECT_ID");

        foreach (Topic topic in client.ListTopics(projectName))
        {
            Console.WriteLine(topic.Name);
        }
        // </ListTopics>
    }
    public async Task ListTopicsAsync()
    {
        // <ListTopicsAsync>
        PublisherClient client = PublisherClient.Create();

        // Alternative: use a known project resource name:
        // projects/{PROJECT_ID}
        string projectName = PublisherClient.GetProjectName("{PROJECT_ID}");
        IAsyncEnumerable <Topic> topics = client.ListTopicsAsync(projectName);
        await topics.ForEachAsync(topic =>
        {
            Console.WriteLine(topic.Name);
        });

        // </ListTopicsAsync>
    }