add idToken from token response

google-oauth-client/src/main/java/com/google/api/client/auth/oauth2/Credential.java

@@ -129,6 +129,9 @@ public interface AccessMethod {
   /** Access token issued by the authorization server. */
   private String accessToken;
 
+  /** Id token issued by the authorization server. */
+  private String idToken;
+
   /**
    * Expected expiration time in milliseconds based on {@link #setExpiresInSeconds} or {@code null}
    * for none.
@@ -316,6 +319,36 @@ public Credential setAccessToken(String accessToken) {
     return this;
   }
 
+  /** Returns the id token or {@code null} for none. */
+  public final String getIdToken() {
+    lock.lock();
+    try {
+      return idToken;
+    } finally {
+      lock.unlock();
+    }
+  }
+
+  /**
+   * Sets the access token.
+   *
+   * <p>
+   * Overriding is only supported for the purpose of calling the super implementation and changing
+   * the return type, but nothing else.
+   * </p>
+   *
+   * @param idToken id token or {@code null} for none
+   */
+  public Credential setIdToken(String idToken) {
+    lock.lock();
+    try {
+      this.idToken = idToken;
+    } finally {
+      lock.unlock();
+    }
+    return this;
+  }
+
   /**
    * Return the method of presenting the access token to the resource server (for example
    * {@link BearerToken.AuthorizationHeaderAccessMethod}).
@@ -534,6 +567,7 @@ public final boolean refreshToken() throws IOException {
    */
   public Credential setFromTokenResponse(TokenResponse tokenResponse) {
     setAccessToken(tokenResponse.getAccessToken());
+    setIdToken(tokenResponse.getIdToken());
     // handle case of having a refresh token previous, but no refresh token in current
     // response
     if (tokenResponse.getRefreshToken() != null) {

google-oauth-client/src/main/java/com/google/api/client/auth/oauth2/TokenResponse.java

@@ -34,6 +34,10 @@ public class TokenResponse extends GenericJson {
   /** Access token issued by the authorization server. */
   @Key("access_token")
   private String accessToken;
+
+  /** ID token issued by the authorization server. */
+  @Key("id_token")
+  private String idToken;
 
   /**
    * Token type (as specified in <a href="http://tools.ietf.org/html/rfc6749#section-7.1">Access
@@ -68,7 +72,7 @@ public class TokenResponse extends GenericJson {
   public final String getAccessToken() {
     return accessToken;
   }
-
+  
   /**
    * Sets the access token issued by the authorization server.
    *
@@ -82,6 +86,24 @@ public TokenResponse setAccessToken(String accessToken) {
     return this;
   }
 
+  /** Returns the id token issued by the authorization server. */
+  public String getIdToken() {
+    return idToken;
+  }
+
+  /**
+   * Sets the id token issued by the authorization server.
+   *
+   * <p>
+   * Overriding is only supported for the purpose of calling the super implementation and changing
+   * the return type, but nothing else.
+   * </p>
+   */
+  public TokenResponse setIdToken( String idToken ) {
+    this.idToken = Preconditions.checkNotNull(idToken);
+    return this;
+  }
+
   /**
    * Returns the token type (as specified in <a
    * href="http://tools.ietf.org/html/rfc6749#section-7.1">Access Token Types</a>).