code: public PathMapped<ServiceConfig> findServiceConfig(PathMappingContext mappingCtx) {
          requireNonNull(mappingCtx, "mappingCtx");
          return router.find(mappingCtx);
      }
docs: Finds the {@link Service} whose {@link Router} matches the {@link PathMappingContext}.
  
  @param mappingCtx a context to find the {@link Service}.
  
  @return the {@link ServiceConfig} wrapped by a {@link PathMapped} if there's a match.
  {@link PathMapped#empty()} if there's no match.