@Override
    public DeviceId deviceId() {
        return deviceId;
    }
@Test
    public void basics() {
        DefaultTopologyVertex v = new DefaultTopologyVertex(D1);
        assertEquals("incorrect device id", D1, v.deviceId());

        new EqualsTester()
                .addEqualityGroup(new DefaultTopologyVertex(D1),
                                  new DefaultTopologyVertex(D1))
                .addEqualityGroup(new DefaultTopologyVertex(D2),
                                  new DefaultTopologyVertex(D2)).testEquals();
    }