code: private Javalin addWsHandler(@NotNull WsHandlerType handlerType, @NotNull String path, @NotNull Consumer<WsHandler> wsHandler, @NotNull Set<Role> roles) {
          wsServlet.addHandler(handlerType, path, wsHandler, roles);
          eventManager.fireWsHandlerAddedEvent(new WsHandlerMetaInfo(handlerType, Util.prefixContextPath(servlet.getConfig().contextPath, path), wsHandler, roles));
          return this;
      }
docs: Adds a specific WebSocket handler for the given path to the instance.
  Requires an access manager to be set on the instance.