code: public List<Variant> getVariants() {
          List<Variant> vs = new ArrayList<Variant>();
          for (Map.Entry<String, ProvFormat> entry : mimeTypeRevMap.entrySet()) {
              if (isOutputFormat(entry.getValue())) {
                  String[] parts = entry.getKey().split("/");
                  MediaType m = new MediaType(parts[0], parts[1]);
                  vs.add(new Variant(m, (java.util.Locale) null, (String) null));
              }
          }
          return vs;
      }
docs: Support for content negotiation, jax-rs style. Create a list of media
  type supported by the framework.
  @see <a href="http://docs.oracle.com/javaee/6/tutorial/doc/gkqbq.html">Content Negotiation</a>