private LinkKey(ConnectPoint src, ConnectPoint dst) {
        this.src = checkNotNull(src);
        this.dst = checkNotNull(dst);
    }
@Test
    public void testCompareNotEquals() {
        LinkKey k1 = LinkKey.linkKey(SRC1, DST1);
        LinkKey k2 = LinkKey.linkKey(SRC1, DST2);

        assertThat(k1, is(not(equalTo(k2))));
        assertThat(k1, is(not(equalTo(new Object()))));
    }