class MonetaryAmountMinValidator implements ConstraintValidator<MonetaryMin, MonetaryAmount> {

   @Override
   public boolean isValid(MonetaryAmount value,
                          ConstraintValidatorContext context) {
      if (value == null) {
         return true;
      }
      return value.isGreaterThanOrEqualTo(value.getFactory().setNumber(number).create());
   }

}