code: private static boolean isValidFileSystemUri(URI uri) {
      // would like to just check null, but fragment appears to be the empty string when not present
      return isNullOrEmpty(uri.getPath())
          && isNullOrEmpty(uri.getQuery())
          && isNullOrEmpty(uri.getFragment());
    }
docs: Returns whether or not the given URI is valid as a base file system URI. It must not have a
  path, query or fragment.