private DeviceId(URI uri) {
        this.uri = uri;
        this.str = uri.toString().toLowerCase();
    }
@Test
    public void basics() {
        new EqualsTester()
                .addEqualityGroup(deviceId("of:foo"),
                                  deviceId("of:foo"))
                .addEqualityGroup(deviceId("of:bar"))
                .testEquals();
    }