equal

@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Zone zone = (Zone) o;

        if (!id.equals(zone.id)) return false;
        if (name != null ? !name.equals(zone.name) : zone.name != null) return false;
        if (code != null ? !code.equals(zone.code) : zone.code != null) return false;
        if (source != zone.source) return false;
        return order != null ? order.equals(zone.order) : zone.order == null;

    }

    @Override
    public int hashCode() {
        int result = id.hashCode();
        result = 31 * result + (name != null ? name.hashCode() : 0);
        result = 31 * result + (code != null ? code.hashCode() : 0);
        result = 31 * result + (source != null ? source.hashCode() : 0);
        result = 31 * result + (order != null ? order.hashCode() : 0);
        return result;
    }