code: public static <FACETTYPE extends Facet<?>> Set<Class<FACETTYPE>> getOptionalFacets(final Class<?> inspectedType)
     {
        return getRelatedFacets(inspectedType, FacetConstraintType.OPTIONAL);
     }
docs: Inspect the given {@link Class} for any {@link FacetConstraintType#OPTIONAL} dependency {@link Facet} types.