code: @Override
    @VisibleForTesting
    protected void configureBuckets(GoogleCloudStorageFileSystem gcsFs) throws IOException {
      rootBucket = initUri.getAuthority();
      checkArgument(rootBucket != null, "No bucket specified in GCS URI: %s", initUri);
      // Validate root bucket name
      pathCodec.getPath(rootBucket, /* objectName= */ null, /* allowEmptyObjectName= */ true);
      logger.atFine().log(
          "GHFS.configureBuckets: GoogleHadoopFileSystem root in bucket: %s", rootBucket);
    }
docs: Sets and validates the root bucket.