Epoch time

public class EpochTimeValidator implements ConstraintValidator<EpochTime, Long> {

    @Override
    public void initialize(EpochTime constraintAnnotation) {
    }

    @Override
    public boolean isValid(Long time, ConstraintValidatorContext constraintValidatorContext) {
        long nowInEpochTime = LocalDateTime.now(ZoneOffset.UTC).toEpochSecond(ZoneOffset.ofHours(0));
        return time != null && time >= 0 && time <= nowInEpochTime;
    }

}

public class EpochTimeValidatorTest {

    private final ConstraintValidator<EpochTime, Long> constraintValidator = new EpochTimeValidator();

    @Test
    public void shouldBeValid() {
        // when
        long time = LocalDateTime.now(ZoneOffset.UTC).toEpochSecond(ZoneOffset.ofHours(0));
        boolean isValid = constraintValidator.isValid(time, null);

        // then
        assertEquals(isValid, true);
    }

    @Test
    public void shouldBeInvalidWhenTimeIsInTheFuture() {
        // when
        long time = LocalDateTime.now(ZoneOffset.UTC).plusSeconds(1).toEpochSecond(ZoneOffset.ofHours(0));
        boolean isValid = constraintValidator.isValid(time, null);

        // then
        assertEquals(isValid, false);
    }

    @Test
    public void shouldBeInvalidWhenTimeIsNegative() {
        // when
        long time = -100;
        boolean isValid = constraintValidator.isValid(time, null);

        // then
        assertEquals(isValid, false);
    }

}