@Override
    public <T> Set<DiscreteResource> valuesOf(Class<T> cls) {
        return ImmutableSet.of();
    }
@Test
    public void testValuesOf() {
        // doesn't match any types of resources
        assertThat(sut.valuesOf(Object.class), is(ImmutableSet.of()));
        assertThat(sut.valuesOf(VlanId.class), is(ImmutableSet.of()));
    }