code: static boolean isDirectory(GoogleCloudStorageItemInfo itemInfo) {
      return isGlobalRoot(itemInfo)
          || itemInfo.isBucket()
          || objectHasDirectoryPath(itemInfo.getObjectName());
    }
docs: Indicates whether {@code itemInfo} is a directory; static version of {@link #isDirectory()}
  to avoid having to create a FileInfo object just to use this logic.