sS javaValueToHTML(O value, Set seen default identityHashSet()) {
  if (!seen.add(value)) ret "see above";
  if (value cast S)
    ret htmlEncode_quote(value);
  else if (value cast L)
    ret ol(map(value, v -> javaValueToHTML(v, seen)));
  else
    ret htmlEncode(shorten(str(value)));
}