svoid setOptAllDyn_pcall(DynamicObject o, MapSO fields) {
  if (fields == null) ret;
  HashMap<S, Field> fieldMap = instanceFieldsMap(o);
  for (Map.Entry<S, O> e : fields.entrySet()) pcall {
    S field = e.getKey();
    O val = e.getValue();
    bool has = fieldMap.containsKey(field);
    if (has)
      setOpt(o, field, val);
    else {
      o.fieldValues = syncMapPut2_createLinkedHashMap(o.fieldValues, intern(field), val);
      ifdef setOptAllDyn_debug
        print("setOptAllDyn added dyn " + field + " to " + o + " [value: " + val + ", fieldValues = " + systemHashCode(o.fieldValues) + ", " + struct(keys(o.fieldValues)) + "]");
      endifdef
    }
  }
}

Began life as a copy of #1029607