Что не нравиться валидатору?

package com.javarush.task.task20.task2002; import java.util.Date; public class User { private String firstName; private String lastName; private Date birthDate; private boolean isMale; private Country country; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public Date getBirthDate() { return birthDate; } public void setBirthDate(Date birthDate) { this.birthDate = birthDate; } public boolean isMale() { return isMale; } public void setMale(boolean male) { isMale = male; } public Country getCountry() { return country; } public void setCountry(Country country) { this.country = country; } public static enum Country { UKRAINE("Ukraine"), RUSSIA("Russia"), OTHER("Other"); private String name; private Country(String name) { this.name = name; } public String getDisplayName() { return this.name; } } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; User user = (User) o; if (isMale != user.isMale) return false; if (firstName != null ? !firstName.equals(user.firstName) : user.firstName != null) return false; if (lastName != null ? !lastName.equals(user.lastName) : user.lastName != null) return false; if (birthDate != null ? !birthDate.equals(user.birthDate) : user.birthDate != null) return false; return country == user.country; } @Override public int hashCode() { int result = firstName != null ? firstName.hashCode() : 0; result = 31 * result + (lastName != null ? lastName.hashCode() : 0); result = 31 * result + (birthDate != null ? birthDate.hashCode() : 0); result = 31 * result + (isMale ? 1 : 0); result = 31 * result + (country != null ? country.hashCode() : 0); return result; } }