code: public static Set<IRI> triplePreferences(final Prefer prefer) {
          final Set<IRI> include = new HashSet<>(DEFAULT_REPRESENTATION);
          if (prefer != null) {
              if (prefer.getInclude().contains(LDP.PreferMinimalContainer.getIRIString())) {
                  include.remove(LDP.PreferContainment);
                  include.remove(LDP.PreferMembership);
              }
              if (prefer.getOmit().contains(LDP.PreferMinimalContainer.getIRIString())) {
                  include.remove(Trellis.PreferUserManaged);
              }
              prefer.getOmit().stream().map(rdf::createIRI).forEach(include::remove);
              prefer.getInclude().stream().map(rdf::createIRI)
                  .filter(iri -> !ignoredPreferences.contains(iri)).forEach(include::add);
          }
          return include;
      }
docs: Get a collection of IRIs for identifying the categories of triples to retrieve.
  
  @param prefer the Prefer header
  @return the categories of triples to retrieve