Using FieldMask for Google Cloud Client Libraries

curl -s -H "Authorization: Bearer `gcloud auth print-access-token`"  \
     "https://storage.googleapis.com/storage/v1/b?project=mineral-minutia-820&projection=noAcl&fields=items(projectNumber)&prettyPrint=false" | jq '.'

project='mineral-minutia-820'

from google.cloud import storage
client = storage.Client(project=project)
for b in client.list_buckets(fields=["items(projectNumber)"]):
   print(b.project_number)

from google.cloud import pubsub_v1
publisher = pubsub_v1.PublisherClient()
project_path = f"projects/{project}"
for topic in publisher.list_topics(request={"project": project_path}, metadata = [("x-goog-fieldmask", "topics(messageStoragePolicy)")] ):
  print(topic)

package main

import (
	"fmt"

	"golang.org/x/net/context"
	googleapiPubsub "google.golang.org/api/pubsub/v1"
	googleapiStorage "google.golang.org/api/storage/v1"
)

const (
	projectID = "mineral-minutia-820"
)

func main() {

	ctx := context.Background()

	storageService, err := googleapiStorage.NewService(ctx)
	if err != nil {
		panic(err)
	}

	pageToken := ""
	for {
		bucketsListReq := storageService.Buckets.List(projectID).Fields("items/projectNumber")
		if pageToken != "" {
			bucketsListReq.PageToken(pageToken)
		}
		r, err := bucketsListReq.Do()
		if err != nil {
			fmt.Printf("Unable to retrieve buckets: %v", err)
			break
		}
		for _, bkt := range r.Items {
			fmt.Printf("Bucket ProjectNumber: %d\n", bkt.ProjectNumber)
		}

		if r.NextPageToken == "" {
			break
		}
		pageToken = r.NextPageToken
	}

	// *******************************************

	pubsubService, err := googleapiPubsub.NewService(ctx)
	if err != nil {
		panic(err)
	}

	pageToken = ""
	for {
		topicsListReq := pubsubService.Projects.Topics.List(fmt.Sprintf("projects/%s", projectID)).Fields("topics/messageStoragePolicy")
		if pageToken != "" {
			topicsListReq.PageToken(pageToken)
		}
		r, err := topicsListReq.Do()
		if err != nil {
			fmt.Printf("Unable to retrieve topics: %v", err)
			break
		}
		for _, t := range r.Topics {
			fmt.Printf("Topics MessagePolicy: %v\n", t.MessageStoragePolicy)
		}

		if r.NextPageToken == "" {
			break
		}
		pageToken = r.NextPageToken
	}

}

package com.test;

import com.google.cloud.pubsub.v1.TopicAdminClient;
import com.google.cloud.pubsub.v1.TopicAdminClient.ListTopicsPagedResponse;
import com.google.cloud.pubsub.v1.TopicAdminSettings;
import com.google.cloud.storage.Bucket;
import com.google.cloud.storage.Storage.BucketField;
import com.google.cloud.storage.Storage.BucketListOption;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import com.google.pubsub.v1.ListTopicsRequest;
import com.google.pubsub.v1.ProjectName;
import com.google.pubsub.v1.Topic;
import com.google.protobuf.Descriptors.FieldDescriptor;

public class TestApp {
	public static void main(String[] args) {
		TestApp tc = new TestApp();
	}

	public TestApp() {
		try {

			//itms(projectNumber)
			Storage storage_service = StorageOptions.newBuilder().build().getService();
			for (Bucket b : storage_service.list(BucketListOption.fields(BucketField.NAME)).iterateAll()) {
				System.out.println(b);
			}

			TopicAdminClient topicClient = TopicAdminClient.create(TopicAdminSettings.newBuilder().build());

			// https://cloud.google.com/java/docs/reference/protobuf/latest/com.google.protobuf.FieldMask.Builder
			//FieldDescriptor fieldDescriptor = Topic.getDescriptor().findFieldByNumber(Topic.MESSAGE_STORAGE_POLICY_FIELD_NUMBER);

			// PubSubListTopics does not seem to have a way to list fields...
			ListTopicsRequest listTopicsRequest = ListTopicsRequest.newBuilder()
					.setProject(ProjectName.format("mineral-minutia-820")) //.setField(fieldDescriptor, value)
					.build();
				
			ListTopicsPagedResponse response = topicClient.listTopics(listTopicsRequest);
			Iterable<Topic> topics = response.iterateAll();
			for (Topic topic : topics)
				System.out.println(topic);

		} catch (Exception ex) {
			System.out.println("Error:  " + ex);
		}
	}

}

using System;

using Google.Cloud.Storage.V1;
using Google.Cloud.PubSub.V1;
using System.Threading.Tasks;

using Google.Api.Gax.ResourceNames;
using Google.Api.Gax.Grpc;

namespace main
{
    class Program
    {
        const string projectID = "mineral-minutia-820";
        [STAThread]
        static void Main(string[] args)
        {
            new Program().Run().Wait();
        }

        private Task Run()
        {
            var client = StorageClient.Create();
            var options = new ListBucketsOptions { Fields = "items(projectNumber),nextPageToken" };
            foreach (var b in client.ListBuckets(projectID, options))
                Console.WriteLine(b.ProjectNumber);

            PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
            ProjectName projectName = ProjectName.FromProject(projectID);
            CallSettings callSettings = CallSettings.FromFieldMask("topics/messageStoragePolicy");
            foreach (Topic t in publisher.ListTopics(projectName, null, null, callSettings))
                Console.WriteLine(t.MessageStoragePolicy);
            return Task.CompletedTask;
        }
    }
}