docs(samples): modified comments in the samples and minor refactor (#990)

* docs(samples): modified comments in the samples and minor refactor * 🦉 Updates from OwlBot post-processor See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md * modified comments acc to review Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: Sita04

samples/snippets/src/main/java/AuthenticateImplicitWithAdc.java

@@ -16,19 +16,22 @@
 
 // [START auth_cloud_implicit_adc]
 
-import com.google.cloud.compute.v1.Instance;
-import com.google.cloud.compute.v1.InstancesClient;
+import com.google.api.gax.paging.Page;
+import com.google.cloud.storage.Bucket;
+import com.google.cloud.storage.Storage;
+import com.google.cloud.storage.StorageOptions;
 import java.io.IOException;
 
 public class AuthenticateImplicitWithAdc {
 
  public static void main(String[] args) throws IOException {
  // TODO(Developer):
  // 1. Before running this sample,
- // set up ADC as described in https://cloud.google.com/docs/authentication/external/set-up-adc
+ // set up Application Default Credentials as described in
+ // https://cloud.google.com/docs/authentication/external/set-up-adc
  // 2. Replace the project variable below.
- // 3. Make sure that the user account or service account that you are using
- // has the required permissions. For this sample, you must have "compute.instances.list".
+ // 3. Make sure you have the necessary permission to list storage buckets
+ // "storage.buckets.list"
  String projectId = "your-google-cloud-project-id";
  authenticateImplicitWithAdc(projectId);
  }
@@ -37,24 +40,20 @@ public static void main(String[] args) throws IOException {
  // credentials to use.
  public static void authenticateImplicitWithAdc(String project) throws IOException {
 
- String zone = "us-central1-a";
- // This snippet demonstrates how to list instances.
  // *NOTE*: Replace the client created below with the client required for your application.
  // Note that the credentials are not specified when constructing the client.
  // Hence, the client library will look for credentials using ADC.
  //
  // Initialize client that will be used to send requests. This client only needs to be created
- // once, and can be reused for multiple requests. After completing all of your requests, call
- // the `instancesClient.close()` method on the client to safely
- // clean up any remaining background resources.
- try (InstancesClient instancesClient = InstancesClient.create()) {
- // Set the project and zone to retrieve instances present in the zone.
- System.out.printf("Listing instances from %s in %s:", project, zone);
- for (Instance zoneInstance : instancesClient.list(project, zone).iterateAll()) {
- System.out.println(zoneInstance.getName());
- }
- System.out.println("####### Listing instances complete #######");
+ // once, and can be reused for multiple requests.
+ Storage storage = StorageOptions.newBuilder().setProjectId(project).build().getService();
+
+ System.out.println("Buckets:");
+ Page<Bucket> buckets = storage.list();
+ for (Bucket bucket : buckets.iterateAll()) {
+ System.out.println(bucket.toString());
  }
+ System.out.println("Listed all storage buckets.");
  }
 }
 // [END auth_cloud_implicit_adc]

samples/snippets/src/main/java/IdTokenFromImpersonatedCredentials.java

@@ -31,14 +31,13 @@ public static void main(String[] args) throws IOException {
 
  // Provide the scopes that you might need to request to access Google APIs,
  // depending on the level of access you need.
- // The best practice is to use the cloud-wide scope and use IAM to narrow the permissions.
- // https://cloud.google.com/docs/authentication#authorization_for_services
+ // This example uses the cloud-wide scope and uses IAM to narrow the permissions.
+ // https://cloud.google.com/docs/authentication/external/authorization-gcp
  // For more information, see: https://developers.google.com/identity/protocols/oauth2/scopes
  String scope = "https://www.googleapis.com/auth/cloud-platform";
 
- // The service name for which the id token is requested. Service name refers to the
- // logical identifier of an API service, such as "pubsub.googleapis.com".
- String targetAudience = "iap.googleapis.com";
+ // The service name for which the id token is requested.
+ String targetAudience = "https://example.com";
 
  // The name of the privilege-bearing service account for whom the credential is created.
  String impersonatedServiceAccount = "name@project.service.gserviceaccount.com";
@@ -78,8 +77,8 @@ public static void getIdTokenUsingOAuth2(
  .build();
 
  // Get the ID token.
- // Once you've obtained the ID token, use it to make an authenticated call
- // to the target audience.
+ // Once you've obtained the ID token, you can use it to make an authenticated call to the
+ // target audience.
  String idToken = idTokenCredentials.refreshAccessToken().getTokenValue();
  System.out.println("Generated ID token.");
  }

samples/snippets/src/main/java/IdTokenFromMetadataServer.java

@@ -30,14 +30,13 @@ public static void main(String[] args) throws IOException, GeneralSecurityExcept
  // TODO(Developer): Replace the below variables before running the code.
 
  // The url or target audience to obtain the ID token for.
- String url = "http://www.abc.com";
+ String url = "https://example.com";
 
  getIdTokenFromMetadataServer(url);
  }
 
- // Use the Google Cloud metadata server in the Cloud Run (or AppEngine or Kubernetes etc.,)
- // environment to create an identity token and add it to the HTTP request as part of an
- // Authorization header.
+ // Use the Google Cloud metadata server to create an identity token and add it to the
+ // HTTP request as part of an Authorization header.
  public static void getIdTokenFromMetadataServer(String url) throws IOException {
  // Construct the GoogleCredentials object which obtains the default configuration from your
  // working environment.
@@ -52,8 +51,8 @@ public static void getIdTokenFromMetadataServer(String url) throws IOException {
  .build();
 
  // Get the ID token.
- // Once you've obtained the ID token, use it to make an authenticated call
- // to the target audience.
+ // Once you've obtained the ID token, you can use it to make an authenticated call to the
+ // target audience.
  String idToken = idTokenCredentials.refreshAccessToken().getTokenValue();
  System.out.println("Generated ID token.");
  }

samples/snippets/src/main/java/IdTokenFromServiceAccount.java

@@ -44,7 +44,7 @@ public static void main(String[] args)
  String jsonCredentialPath = "path-to-json-credential-file";
 
  // The url or target audience to obtain the ID token for.
- String targetAudience = "http://www.abc.com";
+ String targetAudience = "https://example.com";
 
  getIdTokenFromServiceAccount(jsonCredentialPath, targetAudience);
  }

samples/snippets/src/main/java/VerifyGoogleIdToken.java

@@ -26,9 +26,8 @@ public static void main(String[] args) {
  // The Google ID token to verify.
  String idToken = "id-token";
 
- // The service name for which the id token is requested. Service name refers to the
- // logical identifier of an API service, such as "pubsub.googleapis.com".
- String targetAudience = "pubsub.googleapis.com";
+ // The service name for which the id token was requested.
+ String targetAudience = "https://example.com";
 
  // To verify id tokens, get the Json Web Key endpoint (jwk).
  // OpenID Connect allows the use of a "Discovery document," a JSON document found at a

samples/snippets/src/test/java/SnippetsIT.java

@@ -95,16 +95,16 @@ private static String getIdTokenFromServiceAccount(
 
  @Test
  public void testIdTokenFromServiceAccount() throws IOException {
- IdTokenFromServiceAccount.getIdTokenFromServiceAccount(CREDENTIALS, "iap.googleapis.com");
+ IdTokenFromServiceAccount.getIdTokenFromServiceAccount(CREDENTIALS, "https://example.com");
  assertThat(stdOut.toString()).contains("Generated ID token.");
  }
 
  @Test
  public void testVerifyGoogleIdToken() throws IOException {
- String idToken = getIdTokenFromServiceAccount(CREDENTIALS, "iap.googleapis.com");
+ String idToken = getIdTokenFromServiceAccount(CREDENTIALS, "https://example.com");
 
  VerifyGoogleIdToken.verifyGoogleIdToken(
- idToken, "iap.googleapis.com", "https://www.googleapis.com/oauth2/v3/certs");
+ idToken, "https://example.com", "https://www.googleapis.com/oauth2/v3/certs");
  }
 
  @Test