@Override
  public DirectoryStream<Path> newDirectoryStream(
      Path dir, DirectoryStream.Filter<? super Path> filter) throws IOException {
    throw new UnsupportedOperationException();
  }
Returns a runnable that, when run, removes the file system with the given URI from this
provider.
jimfs/src/main/java/com/google/common/jimfs/SystemJimfsFileSystemProvider.java