docs: public <CTX> HtmlSanitizer.Policy apply(
        HtmlStreamEventReceiver out, @Nullable HtmlChangeListener<CTX> listener,
        @Nullable CTX context) {
      if (listener == null) {
        return apply(out);
      } else {
        HtmlChangeReporter<CTX> r = new HtmlChangeReporter<CTX>(
            out, listener, context);
        r.setPolicy(apply(r.getWrappedRenderer()));
        return r.getWrappedPolicy();
      }
    }