public final ArrayList<AttackerEntry> getAttackers() {
        if (attackers == null || attackers.size() <= 0) {
            return new ArrayList<>();
        }
        ArrayList<AttackerEntry> ret = new ArrayList<>();
        for (AttackerEntry e : attackers) {
            if (e != null) {
                ret.add(e);
            }
        }
        return ret;
    }