Override getUniverseDomain

Author: mpeddada1

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

@@ -418,6 +418,7 @@ public final String getPrivateKeyId() {
     return privateKeyId;
   }
 
+  @Override
   public final String getUniverseDomain() {
     return universeDomain;
   }