code: public Page<Bucket> authListBuckets() {
      // [START auth_cloud_implicit]
      // If you don't specify credentials when constructing the client, the
      // client library will look for credentials in the environment.
  
      Storage storage = StorageOptions.getDefaultInstance().getService();
  
      Page<Bucket> buckets = storage.list();
      for (Bucket bucket : buckets.iterateAll()) {
        // do something with the info
      }
      // [END auth_cloud_implicit]
      return buckets;
    }
docs: Example of default auth