@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Mail mail = (Mail) o;
if (key != null ? !key.equals(mail.key) : mail.key != null) return false;
return true;
}
@Override
public int hashCode() {
return key != null ? key.hashCode() : 0;
}
public Long getKey() {
return null == key ? null : key.getKey();
}