code: public void wrapHandler(String path, Class<?> handler) {
          Method[] methods = handler.getMethods();
          Map<Class<? extends Annotation>, Method> cache = new HashMap<>(3);
          cacheMethod(cache, methods, OnOpen.class);
          cacheMethod(cache, methods, OnMessage.class);
          cacheMethod(cache, methods, OnClose.class);
          if (cache.size() > 0) {
              methodCache.put(path, cache);
              handlers.put(path,handler);
          } else {
              throw new RuntimeException("Do not found any annotation of [@OnOpen / @OnMessage / @OnClose] in class: " + handler.getName());
          }
      }
docs: add @WebSocket handler mapper
  
  @param path
  @param handler