code: protected void nextHandler(HttpServerExchange exchange) throws Exception {
          if (this.attachment.hasBasicAuthentication()) {
              HttpHandler httpHandler = RequestUtils.wrapBasicAuthentication(
                      Application.getInstance(LocaleHandler.class),
                      this.attachment.getUsername(),
                      getPassword());
              
              httpHandler.handleRequest(exchange);
          } else {
              Application.getInstance(LocaleHandler.class).handleRequest(exchange);    
          }
      }
docs: Handles the next request in the handler chain
  
  @param exchange The HttpServerExchange
  @throws Exception Thrown when an exception occurs