@Override
    public List<PortStatistics> getPortStatistics(DeviceId deviceId) {
        checkNotNull(deviceId, DEVICE_NULL);
        // TODO not supported at the moment.
        return ImmutableList.of();
    }
@Test
    public void testGetPortStatistics() {
        manager.registerTenantId(TenantId.tenantId(tenantIdValue1));
        VirtualNetwork virtualNetwork = manager.createVirtualNetwork(TenantId.tenantId(tenantIdValue1));
        VirtualDevice virtualDevice = manager.createVirtualDevice(virtualNetwork.id(), DID1);
        manager.createVirtualDevice(virtualNetwork.id(), DID2);

        DeviceService deviceService = manager.get(virtualNetwork.id(), DeviceService.class);

        // test the getPortStatistics() method
        assertEquals("The port statistics set size did not match.", 0,
                     deviceService.getPortStatistics(DID1).size());
    }