@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Ballot ballot = (Ballot) o;
if (id == null || ballot.id == null) return false;
return id.equals(ballot.id);
}
@Override
public int hashCode() {
return id != null ? id.hashCode() : -1;
}