xref: /external/google-cloud-java/java-appengine-admin/google-cloud-appengine-admin/src/main/java/com/google/appengine/v1/InstancesClient.java

/*
 * Copyright 2022 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.appengine.v1;

import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutures;
import com.google.api.core.BetaApi;
import com.google.api.gax.core.BackgroundResource;
import com.google.api.gax.httpjson.longrunning.OperationsClient;
import com.google.api.gax.longrunning.OperationFuture;
import com.google.api.gax.paging.AbstractFixedSizeCollection;
import com.google.api.gax.paging.AbstractPage;
import com.google.api.gax.paging.AbstractPagedListResponse;
import com.google.api.gax.rpc.OperationCallable;
import com.google.api.gax.rpc.PageContext;
import com.google.api.gax.rpc.UnaryCallable;
import com.google.appengine.v1.stub.InstancesStub;
import com.google.appengine.v1.stub.InstancesStubSettings;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.longrunning.Operation;
import com.google.protobuf.Empty;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.TimeUnit;
import javax.annotation.Generated;

// AUTO-GENERATED DOCUMENTATION AND CLASS.
/**
 * Service Description: Manages instances of a version.
 *
 * <p>This class provides the ability to make remote calls to the backing service through method
 * calls that map to API methods. Sample code to get started:
 *
 * <pre>{@code
 * // This snippet has been automatically generated and should be regarded as a code template only.
 * // It will require modifications to work:
 * // - It may require correct/in-range values for request initialization.
 * // - It may require specifying regional endpoints when creating the service client as shown in
 * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 * try (InstancesClient instancesClient = InstancesClient.create()) {
 *   GetInstanceRequest request = GetInstanceRequest.newBuilder().setName("name3373707").build();
 *   Instance response = instancesClient.getInstance(request);
 * }
 * }</pre>
 *
 * <p>Note: close() needs to be called on the InstancesClient object to clean up resources such as
 * threads. In the example above, try-with-resources is used, which automatically calls close().
 *
 * <p>The surface of this class includes several types of Java methods for each of the API's
 * methods:
 *
 * <ol>
 *   <li>A "flattened" method. With this type of method, the fields of the request type have been
 *       converted into function parameters. It may be the case that not all fields are available as
 *       parameters, and not every API method will have a flattened method entry point.
 *   <li>A "request object" method. This type of method only takes one parameter, a request object,
 *       which must be constructed before the call. Not every API method will have a request object
 *       method.
 *   <li>A "callable" method. This type of method takes no parameters and returns an immutable API
 *       callable object, which can be used to initiate calls to the service.
 * </ol>
 *
 * <p>See the individual methods for example code.
 *
 * <p>Many parameters require resource names to be formatted in a particular way. To assist with
 * these names, this class includes a format method for each type of name, and additionally a parse
 * method to extract the individual identifiers contained within names that are returned.
 *
 * <p>This class can be customized by passing in a custom instance of InstancesSettings to create().
 * For example:
 *
 * <p>To customize credentials:
 *
 * <pre>{@code
 * // This snippet has been automatically generated and should be regarded as a code template only.
 * // It will require modifications to work:
 * // - It may require correct/in-range values for request initialization.
 * // - It may require specifying regional endpoints when creating the service client as shown in
 * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 * InstancesSettings instancesSettings =
 *     InstancesSettings.newBuilder()
 *         .setCredentialsProvider(FixedCredentialsProvider.create(myCredentials))
 *         .build();
 * InstancesClient instancesClient = InstancesClient.create(instancesSettings);
 * }</pre>
 *
 * <p>To customize the endpoint:
 *
 * <pre>{@code
 * // This snippet has been automatically generated and should be regarded as a code template only.
 * // It will require modifications to work:
 * // - It may require correct/in-range values for request initialization.
 * // - It may require specifying regional endpoints when creating the service client as shown in
 * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 * InstancesSettings instancesSettings =
 *     InstancesSettings.newBuilder().setEndpoint(myEndpoint).build();
 * InstancesClient instancesClient = InstancesClient.create(instancesSettings);
 * }</pre>
 *
 * <p>To use REST (HTTP1.1/JSON) transport (instead of gRPC) for sending and receiving requests over
 * the wire:
 *
 * <pre>{@code
 * // This snippet has been automatically generated and should be regarded as a code template only.
 * // It will require modifications to work:
 * // - It may require correct/in-range values for request initialization.
 * // - It may require specifying regional endpoints when creating the service client as shown in
 * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 * InstancesSettings instancesSettings = InstancesSettings.newHttpJsonBuilder().build();
 * InstancesClient instancesClient = InstancesClient.create(instancesSettings);
 * }</pre>
 *
 * <p>Please refer to the GitHub repository's samples for more quickstart code snippets.
 */
@Generated("by gapic-generator-java")
public class InstancesClient implements BackgroundResource {
  private final InstancesSettings settings;
  private final InstancesStub stub;
  private final OperationsClient httpJsonOperationsClient;
  private final com.google.longrunning.OperationsClient operationsClient;

  /** Constructs an instance of InstancesClient with default settings. */
  public static final InstancesClient create() throws IOException {
    return create(InstancesSettings.newBuilder().build());
  }

  /**
   * Constructs an instance of InstancesClient, using the given settings. The channels are created
   * based on the settings passed in, or defaults for any settings that are not set.
   */
  public static final InstancesClient create(InstancesSettings settings) throws IOException {
    return new InstancesClient(settings);
  }

  /**
   * Constructs an instance of InstancesClient, using the given stub for making calls. This is for
   * advanced usage - prefer using create(InstancesSettings).
   */
  public static final InstancesClient create(InstancesStub stub) {
    return new InstancesClient(stub);
  }

  /**
   * Constructs an instance of InstancesClient, using the given settings. This is protected so that
   * it is easy to make a subclass, but otherwise, the static factory methods should be preferred.
   */
  protected InstancesClient(InstancesSettings settings) throws IOException {
    this.settings = settings;
    this.stub = ((InstancesStubSettings) settings.getStubSettings()).createStub();
    this.operationsClient =
        com.google.longrunning.OperationsClient.create(this.stub.getOperationsStub());
    this.httpJsonOperationsClient = OperationsClient.create(this.stub.getHttpJsonOperationsStub());
  }

  protected InstancesClient(InstancesStub stub) {
    this.settings = null;
    this.stub = stub;
    this.operationsClient =
        com.google.longrunning.OperationsClient.create(this.stub.getOperationsStub());
    this.httpJsonOperationsClient = OperationsClient.create(this.stub.getHttpJsonOperationsStub());
  }

  public final InstancesSettings getSettings() {
    return settings;
  }

  public InstancesStub getStub() {
    return stub;
  }

  /**
   * Returns the OperationsClient that can be used to query the status of a long-running operation
   * returned by another API method call.
   */
  public final com.google.longrunning.OperationsClient getOperationsClient() {
    return operationsClient;
  }

  /**
   * Returns the OperationsClient that can be used to query the status of a long-running operation
   * returned by another API method call.
   */
  @BetaApi
  public final OperationsClient getHttpJsonOperationsClient() {
    return httpJsonOperationsClient;
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Lists the instances of a version.
   *
   * <p>Tip: To aggregate details about instances over time, see the [Stackdriver Monitoring
   * API](https://cloud.google.com/monitoring/api/ref_v3/rest/v3/projects.timeSeries/list).
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   ListInstancesRequest request =
   *       ListInstancesRequest.newBuilder()
   *           .setParent("parent-995424086")
   *           .setPageSize(883849137)
   *           .setPageToken("pageToken873572522")
   *           .build();
   *   for (Instance element : instancesClient.listInstances(request).iterateAll()) {
   *     // doThingsWith(element);
   *   }
   * }
   * }</pre>
   *
   * @param request The request object containing all of the parameters for the API call.
   * @throws com.google.api.gax.rpc.ApiException if the remote call fails
   */
  public final ListInstancesPagedResponse listInstances(ListInstancesRequest request) {
    return listInstancesPagedCallable().call(request);
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Lists the instances of a version.
   *
   * <p>Tip: To aggregate details about instances over time, see the [Stackdriver Monitoring
   * API](https://cloud.google.com/monitoring/api/ref_v3/rest/v3/projects.timeSeries/list).
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   ListInstancesRequest request =
   *       ListInstancesRequest.newBuilder()
   *           .setParent("parent-995424086")
   *           .setPageSize(883849137)
   *           .setPageToken("pageToken873572522")
   *           .build();
   *   ApiFuture<Instance> future = instancesClient.listInstancesPagedCallable().futureCall(request);
   *   // Do something.
   *   for (Instance element : future.get().iterateAll()) {
   *     // doThingsWith(element);
   *   }
   * }
   * }</pre>
   */
  public final UnaryCallable<ListInstancesRequest, ListInstancesPagedResponse>
      listInstancesPagedCallable() {
    return stub.listInstancesPagedCallable();
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Lists the instances of a version.
   *
   * <p>Tip: To aggregate details about instances over time, see the [Stackdriver Monitoring
   * API](https://cloud.google.com/monitoring/api/ref_v3/rest/v3/projects.timeSeries/list).
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   ListInstancesRequest request =
   *       ListInstancesRequest.newBuilder()
   *           .setParent("parent-995424086")
   *           .setPageSize(883849137)
   *           .setPageToken("pageToken873572522")
   *           .build();
   *   while (true) {
   *     ListInstancesResponse response = instancesClient.listInstancesCallable().call(request);
   *     for (Instance element : response.getInstancesList()) {
   *       // doThingsWith(element);
   *     }
   *     String nextPageToken = response.getNextPageToken();
   *     if (!Strings.isNullOrEmpty(nextPageToken)) {
   *       request = request.toBuilder().setPageToken(nextPageToken).build();
   *     } else {
   *       break;
   *     }
   *   }
   * }
   * }</pre>
   */
  public final UnaryCallable<ListInstancesRequest, ListInstancesResponse> listInstancesCallable() {
    return stub.listInstancesCallable();
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Gets instance information.
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   GetInstanceRequest request = GetInstanceRequest.newBuilder().setName("name3373707").build();
   *   Instance response = instancesClient.getInstance(request);
   * }
   * }</pre>
   *
   * @param request The request object containing all of the parameters for the API call.
   * @throws com.google.api.gax.rpc.ApiException if the remote call fails
   */
  public final Instance getInstance(GetInstanceRequest request) {
    return getInstanceCallable().call(request);
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Gets instance information.
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   GetInstanceRequest request = GetInstanceRequest.newBuilder().setName("name3373707").build();
   *   ApiFuture<Instance> future = instancesClient.getInstanceCallable().futureCall(request);
   *   // Do something.
   *   Instance response = future.get();
   * }
   * }</pre>
   */
  public final UnaryCallable<GetInstanceRequest, Instance> getInstanceCallable() {
    return stub.getInstanceCallable();
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Stops a running instance.
   *
   * <p>The instance might be automatically recreated based on the scaling settings of the version.
   * For more information, see "How Instances are Managed" ([standard
   * environment](https://cloud.google.com/appengine/docs/standard/python/how-instances-are-managed)
   * | [flexible
   * environment](https://cloud.google.com/appengine/docs/flexible/python/how-instances-are-managed)).
   *
   * <p>To ensure that instances are not re-created and avoid getting billed, you can stop all
   * instances within the target version by changing the serving status of the version to `STOPPED`
   * with the
   * [`apps.services.versions.patch`](https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1/apps.services.versions/patch)
   * method.
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   DeleteInstanceRequest request =
   *       DeleteInstanceRequest.newBuilder().setName("name3373707").build();
   *   instancesClient.deleteInstanceAsync(request).get();
   * }
   * }</pre>
   *
   * @param request The request object containing all of the parameters for the API call.
   * @throws com.google.api.gax.rpc.ApiException if the remote call fails
   */
  public final OperationFuture<Empty, OperationMetadataV1> deleteInstanceAsync(
      DeleteInstanceRequest request) {
    return deleteInstanceOperationCallable().futureCall(request);
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Stops a running instance.
   *
   * <p>The instance might be automatically recreated based on the scaling settings of the version.
   * For more information, see "How Instances are Managed" ([standard
   * environment](https://cloud.google.com/appengine/docs/standard/python/how-instances-are-managed)
   * | [flexible
   * environment](https://cloud.google.com/appengine/docs/flexible/python/how-instances-are-managed)).
   *
   * <p>To ensure that instances are not re-created and avoid getting billed, you can stop all
   * instances within the target version by changing the serving status of the version to `STOPPED`
   * with the
   * [`apps.services.versions.patch`](https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1/apps.services.versions/patch)
   * method.
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   DeleteInstanceRequest request =
   *       DeleteInstanceRequest.newBuilder().setName("name3373707").build();
   *   OperationFuture<Empty, OperationMetadataV1> future =
   *       instancesClient.deleteInstanceOperationCallable().futureCall(request);
   *   // Do something.
   *   future.get();
   * }
   * }</pre>
   */
  public final OperationCallable<DeleteInstanceRequest, Empty, OperationMetadataV1>
      deleteInstanceOperationCallable() {
    return stub.deleteInstanceOperationCallable();
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Stops a running instance.
   *
   * <p>The instance might be automatically recreated based on the scaling settings of the version.
   * For more information, see "How Instances are Managed" ([standard
   * environment](https://cloud.google.com/appengine/docs/standard/python/how-instances-are-managed)
   * | [flexible
   * environment](https://cloud.google.com/appengine/docs/flexible/python/how-instances-are-managed)).
   *
   * <p>To ensure that instances are not re-created and avoid getting billed, you can stop all
   * instances within the target version by changing the serving status of the version to `STOPPED`
   * with the
   * [`apps.services.versions.patch`](https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1/apps.services.versions/patch)
   * method.
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   DeleteInstanceRequest request =
   *       DeleteInstanceRequest.newBuilder().setName("name3373707").build();
   *   ApiFuture<Operation> future = instancesClient.deleteInstanceCallable().futureCall(request);
   *   // Do something.
   *   future.get();
   * }
   * }</pre>
   */
  public final UnaryCallable<DeleteInstanceRequest, Operation> deleteInstanceCallable() {
    return stub.deleteInstanceCallable();
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Enables debugging on a VM instance. This allows you to use the SSH command to connect to the
   * virtual machine where the instance lives. While in "debug mode", the instance continues to
   * serve live traffic. You should delete the instance when you are done debugging and then allow
   * the system to take over and determine if another instance should be started.
   *
   * <p>Only applicable for instances in App Engine flexible environment.
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   DebugInstanceRequest request =
   *       DebugInstanceRequest.newBuilder()
   *           .setName("name3373707")
   *           .setSshKey("sshKey-893236425")
   *           .build();
   *   Instance response = instancesClient.debugInstanceAsync(request).get();
   * }
   * }</pre>
   *
   * @param request The request object containing all of the parameters for the API call.
   * @throws com.google.api.gax.rpc.ApiException if the remote call fails
   */
  public final OperationFuture<Instance, OperationMetadataV1> debugInstanceAsync(
      DebugInstanceRequest request) {
    return debugInstanceOperationCallable().futureCall(request);
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Enables debugging on a VM instance. This allows you to use the SSH command to connect to the
   * virtual machine where the instance lives. While in "debug mode", the instance continues to
   * serve live traffic. You should delete the instance when you are done debugging and then allow
   * the system to take over and determine if another instance should be started.
   *
   * <p>Only applicable for instances in App Engine flexible environment.
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   DebugInstanceRequest request =
   *       DebugInstanceRequest.newBuilder()
   *           .setName("name3373707")
   *           .setSshKey("sshKey-893236425")
   *           .build();
   *   OperationFuture<Instance, OperationMetadataV1> future =
   *       instancesClient.debugInstanceOperationCallable().futureCall(request);
   *   // Do something.
   *   Instance response = future.get();
   * }
   * }</pre>
   */
  public final OperationCallable<DebugInstanceRequest, Instance, OperationMetadataV1>
      debugInstanceOperationCallable() {
    return stub.debugInstanceOperationCallable();
  }

  // AUTO-GENERATED DOCUMENTATION AND METHOD.
  /**
   * Enables debugging on a VM instance. This allows you to use the SSH command to connect to the
   * virtual machine where the instance lives. While in "debug mode", the instance continues to
   * serve live traffic. You should delete the instance when you are done debugging and then allow
   * the system to take over and determine if another instance should be started.
   *
   * <p>Only applicable for instances in App Engine flexible environment.
   *
   * <p>Sample code:
   *
   * <pre>{@code
   * // This snippet has been automatically generated and should be regarded as a code template only.
   * // It will require modifications to work:
   * // - It may require correct/in-range values for request initialization.
   * // - It may require specifying regional endpoints when creating the service client as shown in
   * // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
   * try (InstancesClient instancesClient = InstancesClient.create()) {
   *   DebugInstanceRequest request =
   *       DebugInstanceRequest.newBuilder()
   *           .setName("name3373707")
   *           .setSshKey("sshKey-893236425")
   *           .build();
   *   ApiFuture<Operation> future = instancesClient.debugInstanceCallable().futureCall(request);
   *   // Do something.
   *   Operation response = future.get();
   * }
   * }</pre>
   */
  public final UnaryCallable<DebugInstanceRequest, Operation> debugInstanceCallable() {
    return stub.debugInstanceCallable();
  }

  @Override
  public final void close() {
    stub.close();
  }

  @Override
  public void shutdown() {
    stub.shutdown();
  }

  @Override
  public boolean isShutdown() {
    return stub.isShutdown();
  }

  @Override
  public boolean isTerminated() {
    return stub.isTerminated();
  }

  @Override
  public void shutdownNow() {
    stub.shutdownNow();
  }

  @Override
  public boolean awaitTermination(long duration, TimeUnit unit) throws InterruptedException {
    return stub.awaitTermination(duration, unit);
  }

  public static class ListInstancesPagedResponse
      extends AbstractPagedListResponse<
          ListInstancesRequest,
          ListInstancesResponse,
          Instance,
          ListInstancesPage,
          ListInstancesFixedSizeCollection> {

    public static ApiFuture<ListInstancesPagedResponse> createAsync(
        PageContext<ListInstancesRequest, ListInstancesResponse, Instance> context,
        ApiFuture<ListInstancesResponse> futureResponse) {
      ApiFuture<ListInstancesPage> futurePage =
          ListInstancesPage.createEmptyPage().createPageAsync(context, futureResponse);
      return ApiFutures.transform(
          futurePage,
          input -> new ListInstancesPagedResponse(input),
          MoreExecutors.directExecutor());
    }

    private ListInstancesPagedResponse(ListInstancesPage page) {
      super(page, ListInstancesFixedSizeCollection.createEmptyCollection());
    }
  }

  public static class ListInstancesPage
      extends AbstractPage<
          ListInstancesRequest, ListInstancesResponse, Instance, ListInstancesPage> {

    private ListInstancesPage(
        PageContext<ListInstancesRequest, ListInstancesResponse, Instance> context,
        ListInstancesResponse response) {
      super(context, response);
    }

    private static ListInstancesPage createEmptyPage() {
      return new ListInstancesPage(null, null);
    }

    @Override
    protected ListInstancesPage createPage(
        PageContext<ListInstancesRequest, ListInstancesResponse, Instance> context,
        ListInstancesResponse response) {
      return new ListInstancesPage(context, response);
    }

    @Override
    public ApiFuture<ListInstancesPage> createPageAsync(
        PageContext<ListInstancesRequest, ListInstancesResponse, Instance> context,
        ApiFuture<ListInstancesResponse> futureResponse) {
      return super.createPageAsync(context, futureResponse);
    }
  }

  public static class ListInstancesFixedSizeCollection
      extends AbstractFixedSizeCollection<
          ListInstancesRequest,
          ListInstancesResponse,
          Instance,
          ListInstancesPage,
          ListInstancesFixedSizeCollection> {

    private ListInstancesFixedSizeCollection(List<ListInstancesPage> pages, int collectionSize) {
      super(pages, collectionSize);
    }

    private static ListInstancesFixedSizeCollection createEmptyCollection() {
      return new ListInstancesFixedSizeCollection(null, 0);
    }

    @Override
    protected ListInstancesFixedSizeCollection createCollection(
        List<ListInstancesPage> pages, int collectionSize) {
      return new ListInstancesFixedSizeCollection(pages, collectionSize);
    }
  }
}