@Test(expected = IllegalStateException.class)
public void getFacet_fails_for_multiple_facet_implementation()
{

    List<Plugin> plugins = new ArrayList<>();
    OneFacetPlugin oneFacetPlugin = new OneFacetPlugin();
    TwoFacetPlugin twoFacetPlugin = new TwoFacetPlugin();
    plugins.add(oneFacetPlugin);
    plugins.add(twoFacetPlugin);
    FacetRegistry registry = new FacetRegistry(plugins);
    registry.getFacet(Facet1.class);
}