docs: public Optional<URL> resolve(String resourcePath) {
          for (Map.Entry<String, List<ResourceLoader>> entry : resourceMappings.entrySet()) {
              List<ResourceLoader> loaders = entry.getValue();
              String mapping = entry.getKey();
              if (!loaders.isEmpty() && pathMatcher.matches(mapping, resourcePath)) {
                  String path = pathMatcher.extractPathWithinPattern(mapping, resourcePath);
                  //A request to the root of the mapping
                  if (StringUtils.isEmpty(path)) {
                      path = INDEX_PAGE;
                  }
                  if (path.startsWith("/")) {
                      path = path.substring(1);
                  }
                  for (ResourceLoader loader : loaders) {
                      Optional<URL> resource = loader.getResource(path);
                      if (resource.isPresent()) {
                          return resource;
                      } else {
                          if (path.indexOf('.') == -1) {
                              if (!path.endsWith("/")) {
                                  path = path + "/";
                              }
                              path += INDEX_PAGE;
                              resource = loader.getResource(path);
                              if (resource.isPresent()) {
                                  return resource;
                              }
                          }
                      }
                  }
              }
          }
  
          return Optional.empty();
      }