code: public Route produces(String... types) {
          Preconditions.checkNotNull(types);
          final ImmutableSet.Builder<MediaType> builder = new ImmutableSet.Builder<>();
          builder.addAll(this.producedMediaTypes);
          for (String s : types) {
              final MediaType mt = MediaType.parse(s);
              if (mt.hasWildcard()) {
                  throw new RoutingException("A route cannot `produce` a mime type with a wildcard: " + mt);
              }
              builder.add(mt);
          }
          this.producedMediaTypes = builder.build();
          return this;
      }
docs: Sets the set of media types produced by the route.
  
  @param types the set of type
  @return the current route