public ValidationRuleResult apply() {

    logger.info("apply()=> BEGIN");
    if (getUserName() == null) {
      return null;
    }

    ValidationRuleResult result = new ValidationRuleResult();

    checkUnique(result);
    if (result.isFailed()) {
      return result;
    }

    logger.info("apply()=> END, SUCCESS");

    result.success();

    return result;
  }