public void clearCache(ClassLoader classLoader) {
        if (classLoader == null) {
            return;
        }
        requestClassCache.remove(classLoader);
        responseClassCache.remove(classLoader);
    }
Fetch request class for cache according  service and method

@param service    interface name
@param methodName method name
@return request class
codec/codec-jackson/src/main/java/com/alipay/sofa/rpc/codec/jackson/JacksonHelper.java