private HostId(MacAddress mac, VlanId vlanId) {
        this.mac = mac;
        this.vlanId = vlanId;
    }
@Test
    public void basics() {
        new EqualsTester()
                .addEqualityGroup(hostId(MAC1, VLAN1), hostId(MAC1, VLAN1))
                .addEqualityGroup(hostId(MAC2, VLAN2), hostId(MAC2, VLAN2))
                .testEquals();
    }