code: public static <T> T asFacet(Class<T> facetType, Faceted subject)
      {
          return subject == null ? null : subject.asFacet(facetType);
      }
docs: Returns a facet of the given subject if supported, returning null
  otherwise.
  <p>
  This does not attempt to cast the subject to the requested type, since
  the {@link Faceted} interface declares the intent to control the
  conversion.
  
  @return the requested facet, or null if {@code subject} is null or if
  subject doesn't support the requested facet type.