code: public void setFromString(String prop, String ...val) {
      if (val.length == 1) {
        String[] vals = val[0].split("[\\s,]+");
        set(prop, vals);
      } else {
        set(prop, val);
      }
    }
docs: Set a transform multi-value giving either a set of strings or
  just an string of values separated by comma.