public class Person {

    private String name;
    private LocalDate birthDate;
    private Double height;
    private int age;
    private Car car;
    private LocalDateTime createdAt;

    //GET, SET
}

public class Car {

    private String manufacturer;
    private String licensePlate;
    private double price;
    private BigDecimal tax;
    private long lifeTime;
    private boolean active;

    //GET, SET
}

public class PersonValidator extends Validator<Person> {

    @Override
    public ValidationResult validate(Person obj) {

        return addNumberRule(Person::getAge, "age", r -> r.notNull().greaterThan(18))
                .addLocalDateTimeRule(Person::getCreatedAt, "created_at", r -> r.notNull().isPast())
                .addLocalDateRule(Person::getBirthDate, "birth_date", r -> r.notNull().isPast())
                .addNumberRule(Person::getHeight, "height", r -> r.notNull().greaterThan(1.70))
                .addCharSequenceRule(Person::getName, "name", r -> r.notNull().notBlank().greaterThanOrEquals(10))
                .addObjectRule(Person::getCar, "car", ObjectRule::notNull)
                .addListRule(Person::getCars, "cars", r -> r.notNull().lessThan(10))
                .run(obj);
    }
}

public class PersonValidator extends Validator<Person> {

    @Override
    public ValidationResult validate(Person obj) {

        CarValidator carValidator = new CarValidator();

        return addNumberRule(Person::getAge, "age", r -> r.notNull().greaterThan(18))
                .addValidator(Person::getCar, carValidator)
                .run(obj);
    }
}

public class CarValidator extends Validator<Car> {

    @Override
    public ValidationResult validate(Car obj) {
        return addCharSequenceRule(Car::getLicensePlate, "person.car.plate", r -> r.isUpperCase().notNull())
                .addNumberRule(Car::getSeatCount, "seat_count", i -> i.notNull().greaterThan(4))
                .addNumberRule(Car::getLifeTime, "life_time", i -> i.notNull().isPositive())
                .addNumberRule(Car::getPrice, "price", i -> i.isPositive().greaterThan(new BigDecimal("30000.00")))
                .addNumberRule(Car::getTax, "tax", i -> i.isPositive().lessThan(new BigDecimal("100000.00")))
                .addBooleanRule(Car::isActive, "active", b -> b.notNull().isTrue())
                .run(obj);
    }
}

class ValidatorTest {

    @Test
    void successTest() {
        PersonValidator personValidator = new PersonValidator();

        Person person = new Person();
        person.setAge(28);
        person.setCreatedAt(LocalDateTime.now().minusDays(1));
        person.setHeight(1.72);
        person.setName("Jean Leal Silva");
        person.setBirthDate(LocalDate.parse("1993-05-22", DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        person.setCar(new Car());
        person.getCar().setActive(true);
        person.getCar().setLifeTime(400);
        person.getCar().setPrice(69990.00);
        person.getCar().setTax(new BigDecimal("69990.00"));
        person.getCar().setManufacturer("vw");
        person.getCar().setLicensePlate("PKY8899");
        person.getCar().setSeatCount(5);

        final ValidationResult validationResult = personValidator.validate(person);
        List<ValidationError> errors = validationResult.getErrors();
        assertTrue(validationResult.isValid());
        assertEquals(0, errors.size());
    }
}

public class PersonValidator extends Validator<Person> {

    @Override
    public ValidationResult validate(Person obj) {

        CarValidator carValidator = new CarValidator();

        return addItemListValidator(Person::getCars, carValidator)
                .run(obj);
    }
}

public class CustomRuleEx extends Rule<String> {

    public CustomRuleEx isNameEqualsJean() {
        this.addPredicate(new RulePredicate<>(s -> s.equals("Jean Leal Silva"), "O nome deve ser igual a Jean Leal Silva."));
        return this;
    }
}

public class PersonValidator extends Validator<Person> {

    @Override
    public ValidationResult validate(Person obj) {

        CarValidator carValidator = new CarValidator();

        return addNumberRule(Person::getAge, "age", r -> r.notNull().greaterThan(18))
                .addCustomRule(Person::getName, "name", CustomRuleEx::new, CustomRuleEx::validate)
                .run(obj);
    }
}

public class PersonValidator extends Validator<Person> {

    @Override
    public ValidationResult validate(Person obj) {

        CarValidator carValidator = new CarValidator();

        return addNumberRule(Person::getAge, "age", r -> r.notNull("Cannot be null").greaterThan(18, "The age must be greater than 18."))
                .run(obj);
    }
}