public PiPreReplica(PortNumber egressPort, int instanceId) {
        this.egressPort = checkNotNull(egressPort);
        this.instanceId = instanceId;
    }
@Test
    public void testPiPreReplica() {
        assertThat("Invalid port", replica1of1.egressPort(), is(port1));
        assertThat("Invalid instance ID", replica1of1.instanceId(), is(instanceId1));
        assertThat("Invalid port", replica1of2.egressPort(), is(port2));
        assertThat("Invalid instance ID", replica1of2.instanceId(), is(instanceId1));
    }