public abstract class AbstractAsteriskIntegerField extends AbstractCisIntegerField {
  public static final Integer ASTERISK = new Integer(-4321); // value is never used

  @Override
  protected String execFormatValue(Integer validValue) {
    if (ASTERISK == validValue) {
      return "*";
    }
    return super.execFormatValue(validValue);
  }
}

      if (valueIsDifferent) {
        getVmaxField().setValue(AbstractAsteriskIntegerField.ASTERISK);
      } else {
        getVmaxField().setValue(commonValue);
      }