弹簧引导验证-二选一不为空

我正在尝试验证两个字段中是否有一个在Spring引导中不为空?

我在方法类中为主要对象设置了:

@NotNull(message = "Username field is required")
private String username;

@NotNull(message = "Email field is required")
private String email;

但这需要两个字段都不为空。然后我使用这里描述的自定义验证 https://lmonkiewicz.com/programming/get-noticed-2017/spring-boot-rest-request-validation/ 但我没能让那个例子起作用。我必须坚持下去

用户类声明:

@CombinedNotNull(fields = {"username","email"})
public class User implements {

    private long id = 0L;
    @NotNull(message = "First name field is required")
    private String firstName;

    @NotNull(message = "Last name field is required")
    private String lastName;

    private String username;
    private String email;

    @NotNull(message = "Status field is required")
    private String status;

    ...all methods here...
    ...setters and getters...

}

CombinedNotNull类:

@Documented
@Retention(RUNTIME)
@Target({ TYPE, ANNOTATION_TYPE })
@Constraint(validatedBy = userValidator.class)
public @interface CombinedNotNull {
        String message() default "username or email is required";
        Class<?>[] groups() default { };
        Class<? extends Payload>[] payload() default { };
}

用户验证程序类:

@Component
public class userValidator implements ConstraintValidator<CombinedNotNull, User> {

    @Override
    public void initialize(final CombinedNotNull combinedNotNull) {
        fields = combinedNotNull.fields();
    }

    @Override
    public boolean isValid(final User user, final ConstraintValidatorContext context) {
        final BeanWrapperImpl beanWrapper = new BeanWrapperImpl(user);

        for (final String f : fields) {
            final Object fieldValue = beanWrapper.getPropertyValue(f);

            if (fieldValue == null) {
                return false;
            }
        }

        return true;
    }
}

有没有其他方法来完成这项工作,或者我应该使用那个页面上的“复杂”示例?