private volatile static AtomicInteger creations = new AtomicInteger(Integer.MIN_VALUE);
private final int creation;

{
    creation = creations.getAndIncrement();
}

@Override
public int hashCode() {
    return creation;
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    if (creation == ((Stuff) obj).creation)
        return true;
    else
        return false;
}