public static int Main(string[] args)
        {
            string projectId = Environment.GetEnvironmentVariable(ProjectEnvironmentVariable);

            if (string.IsNullOrEmpty(projectId))
            {
                Console.WriteLine($"Environment variable {ProjectEnvironmentVariable} must be set.");
                return(1);
            }

            // Create client
            FirestoreAdminClient client = FirestoreAdminClient.Create();

            // Initialize request argument
            ParentName parentName = new ParentName(projectId, "(default)", "collection");

            // Call API method
            var indexes = client.ListIndexes(parentName);

            // Show the result
            foreach (var index in indexes)
            {
                Console.WriteLine(index);
            }

            // Success
            Console.WriteLine("Smoke test passed OK");
            return(0);
        }
        /// <summary>Snippet for ListIndexes</summary>
        public void ListIndexes_RequestObject()
        {
            // Snippet: ListIndexes(ListIndexesRequest,CallSettings)
            // Create client
            FirestoreAdminClient firestoreAdminClient = FirestoreAdminClient.Create();
            // Initialize request argument(s)
            ListIndexesRequest request = new ListIndexesRequest
            {
                ParentAsParentName = new ParentName("[PROJECT]", "[DATABASE]", "[COLLECTION_ID]"),
            };
            // Make the request
            PagedEnumerable <ListIndexesResponse, Index> response =
                firestoreAdminClient.ListIndexes(request);

            // Iterate over all response items, lazily performing RPCs as required
            foreach (Index item in response)
            {
                // Do something with each item
                Console.WriteLine(item);
            }

            // Or iterate over pages (of server-defined size), performing one RPC per page
            foreach (ListIndexesResponse page in response.AsRawResponses())
            {
                // Do something with each page of items
                Console.WriteLine("A page of results:");
                foreach (Index item in page)
                {
                    Console.WriteLine(item);
                }
            }

            // Or retrieve a single page of known size (unless it's the final page), performing as many RPCs as required
            int          pageSize   = 10;
            Page <Index> singlePage = response.ReadPage(pageSize);

            // Do something with the page of items
            Console.WriteLine($"A page of {pageSize} results (unless it's the final page):");
            foreach (Index item in singlePage)
            {
                Console.WriteLine(item);
            }
            // Store the pageToken, for when the next page is required.
            string nextPageToken = singlePage.NextPageToken;
            // End snippet
        }