code: public BaseValidationCheck getValidationChecker(ValidationRule rule) {
          ValidationRule existRule = this.rules.stream().filter(r -> r.getRuleName().equals(rule.getRuleName())).findFirst().orElse(null);
          if (existRule == null) {
              throw new ValidationLibException("rulename : " + rule.getRuleName() + "checker is notfound  ", HttpStatus.INTERNAL_SERVER_ERROR);
          }
          return existRule.getValidationCheck();
      }
docs: Gets validation checker.
  
  @param rule the rule
  @return the validation checker