feat: promote IdToken and JWT features (googleapis#538)

These features have been available for months and have not received bug reports.

Author: chingor13

oauth2_http/java/com/google/auth/oauth2/ComputeEngineCredentials.java

@@ -42,7 +42,6 @@
 import com.google.api.client.util.GenericData;
 import com.google.auth.ServiceAccountSigner;
 import com.google.auth.http.HttpTransportFactory;
-import com.google.common.annotations.Beta;
 import com.google.common.base.Joiner;
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
@@ -212,7 +211,6 @@ public AccessToken refreshAccessToken() throws IOException {
    * @throws IOException if the attempt to get an IdToken failed
    * @return IdToken object which includes the raw id_token, JsonWebSignature
    */
-  @Beta
   @Override
   public IdToken idTokenWithAudience(String targetAudience, List<IdTokenProvider.Option> options)
       throws IOException {

oauth2_http/java/com/google/auth/oauth2/IdToken.java

@@ -33,7 +33,6 @@
 
 import com.google.api.client.json.JsonFactory;
 import com.google.api.client.json.webtoken.JsonWebSignature;
-import com.google.common.annotations.Beta;
 import com.google.common.base.MoreObjects;
 import java.io.IOException;
 import java.io.ObjectInputStream;
@@ -43,7 +42,6 @@
 import java.util.Objects;
 
 /** Represents a temporary IdToken and its JsonWebSignature object */
-@Beta
 public class IdToken extends AccessToken implements Serializable {
 
   private static final long serialVersionUID = -8514239465808977353L;

oauth2_http/java/com/google/auth/oauth2/IdTokenCredentials.java

@@ -32,7 +32,6 @@
 package com.google.auth.oauth2;
 
 import com.google.api.client.util.Preconditions;
-import com.google.common.annotations.Beta;
 import com.google.common.base.MoreObjects;
 import java.io.IOException;
 import java.util.List;
@@ -101,7 +100,6 @@
  * System.out.println(tokenCredential.getIdToken().getJsonWebSignature().getPayload().getExpirationTimeSeconds());
  * </pre>
  */
-@Beta
 public class IdTokenCredentials extends OAuth2Credentials {
 
   private static final long serialVersionUID = -2133257318957588431L;

oauth2_http/java/com/google/auth/oauth2/IdTokenProvider.java

@@ -31,12 +31,10 @@
 
 package com.google.auth.oauth2;
 
-import com.google.common.annotations.Beta;
 import java.io.IOException;
 import java.util.List;
 
 /** Interface for an Google OIDC token provider. This type represents a google issued OIDC token. */
-@Beta
 public interface IdTokenProvider {
 
   /**

oauth2_http/java/com/google/auth/oauth2/ImpersonatedCredentials.java

@@ -45,7 +45,6 @@
 import com.google.auth.ServiceAccountSigner;
 import com.google.auth.http.HttpCredentialsAdapter;
 import com.google.auth.http.HttpTransportFactory;
-import com.google.common.annotations.Beta;
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableMap;
 import java.io.IOException;
@@ -303,7 +302,6 @@ public AccessToken refreshAccessToken() throws IOException {
    * @return IdToken object which includes the raw id_token, expiration, and audience
    * @throws IOException if the attempt to get an ID token failed
    */
-  @Beta
   @Override
   public IdToken idTokenWithAudience(String targetAudience, List<IdTokenProvider.Option> options)
       throws IOException {

oauth2_http/java/com/google/auth/oauth2/JwtProvider.java

@@ -31,10 +31,7 @@
 
 package com.google.auth.oauth2;
 
-import com.google.common.annotations.Beta;
-
 /** Interface for creating custom JWT tokens */
-@Beta
 public interface JwtProvider {
 
   /**

oauth2_http/java/com/google/auth/oauth2/ServiceAccountCredentials.java

@@ -55,7 +55,6 @@
 import com.google.api.client.util.SecurityUtils;
 import com.google.auth.ServiceAccountSigner;
 import com.google.auth.http.HttpTransportFactory;
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
@@ -476,7 +475,6 @@ public boolean isRequired(HttpResponse response) {
    * @throws IOException if the attempt to get an IdToken failed
    * @return IdToken object which includes the raw id_token, expiration and audience
    */
-  @Beta
   @Override
   public IdToken idTokenWithAudience(String targetAudience, List<Option> options)
       throws IOException {

oauth2_http/java/com/google/auth/oauth2/TokenVerifier.java

@@ -41,7 +41,6 @@
 import com.google.api.client.util.Clock;
 import com.google.api.client.util.Key;
 import com.google.auth.http.HttpTransportFactory;
-import com.google.common.annotations.Beta;
 import com.google.common.base.Preconditions;
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
@@ -79,7 +78,6 @@
  * @author Jeff Ching
  * @since 0.21.0
  */
-@Beta
 public class TokenVerifier {
   private static final String IAP_CERT_URL = "https://www.gstatic.com/iap/verify/public_key-jwk";
   private static final String FEDERATED_SIGNON_CERT_URL =