能否将RestServerVerticle的startListen设置为protected的，方便扩展

场景：
1、自定义Verticle继承RestServerVerticle，以同时支持普通HTTP消息和HTTP隧道
2、需要在startListen前重新设置handler，对Connect Method进行特殊处理
当前RestServerVerticle.startListen是private的，导致无法扩展

Start by locating RestServerVerticle and reading the startListen entry point, its handler setup, and the subclassing scenario described in the issue. Check existing tests or usages around this method; done means an extending Verticle can adjust the handler before listening while existing HTTP behavior remains intact.

Written by the indexing model from the issue text.