sbool setOptAllDyn_debug;

static void setOptAllDyn(DynamicObject o, Map<S, O> fields) {
  if (fields == null) ret;
  for (S field : keys(fields)) {
    O val = fields.get(field);
    bool has = hasField(o, field);
    if (has)
      setOpt(o, field, val);
    else {
      o.fieldValues.put(intern(field), val);
      if (setOptAllDyn_debug) print("setOptAllDyn added dyn " + field + " to " + o + " [value: " + val + ", fieldValues = " + systemHashCode(o.fieldValues) + ", " + struct(keys(o.fieldValues)) + "]");
    }
  }
}

Began life as a copy of #1005268