docs: public static Predicate<Quad> filterWithPrefer(final Prefer prefer) {
          final Set<String> include = new HashSet<>(DEFAULT_REPRESENTATION);
          ofNullable(prefer).ifPresent(p -> {
              p.getOmit().forEach(include::remove);
              p.getInclude().forEach(include::add);
          });
          return quad -> quad.getGraphName().filter(x -> x instanceof IRI).map(x -> (IRI) x)
              .map(IRI::getIRIString).filter(include::contains).isPresent();
      }