ServiceComb-Java-Chassis 使用CSERestTemplate访问出现类型转化失败

String jsonResult = restTemplate.getForObject(url, String.class)
出现异常：com.alibaba.fastjson.JSONObject cannot be cast to java.lang.String

java-chassis版本2.6.0

Start by reproducing the reported CSERestTemplate getForObject call with java-chassis 2.6.0 and String.class, then trace the response conversion that produces the JSONObject-to-String cast failure. Done means the same request returns a String without the reported exception, with coverage for the failing conversion path.

Written by the indexing model from the issue text.