@Override
  public Set<String> supportedFileAttributeViews() {
    Set<String> result = new HashSet<>(myLocalFS.supportedFileAttributeViews());
    for (Backend backend : myBackends.get()) {
      result.addAll(backend.fileSystem.supportedFileAttributeViews());
    }
    return result;
  }
@Override
  public Set<String> supportedFileAttributeViews()