code: public static <I extends Request, O extends Response> Router<Service<I, O>> ofCompositeService(
              List<CompositeServiceEntry<I, O>> entries) {
          requireNonNull(entries, "entries");
  
          final Router<CompositeServiceEntry<I, O>> delegate = wrapCompositeServiceRouter(defaultRouter(
                  entries, CompositeServiceEntry::pathMapping,
                  (mapping, existingMapping) -> {
                      final String a = mapping.toString();
                      final String b = existingMapping.toString();
                      if (a.equals(b)) {
                          throw new IllegalStateException(
                                  "Your composite service has a duplicate path mapping: " + a);
                      }
  
                      throw new IllegalStateException(
                              "Your composite service has path mappings with a conflict: " +
                              a + " vs. " + b);
                  }));
  
          return new CompositeRouter<>(delegate, result ->
                  result.isPresent() ? PathMapped.of(result.mapping(), result.mappingResult(),
                                                     result.value().service())
                                     : PathMapped.empty());
      }
docs: Returns the default implementation of the {@link Router} to find a {@link CompositeServiceEntry}.