@SuppressWarnings("unused")
  @Deprecated
  public <F extends Content> Iterator<F> getDescendants(Filter<F> filter) {
    return new FilterIterator<>(new DescendantIterator(this), AbstractFilter.toFilter2(filter));
  }
@SuppressWarnings("unused")
  @Deprecated
  public <F extends Content> Iterator<F> getDescendants(Filter<F> filter)