public JavaType[] getReqClass(String service, String methodName) {

        String key = buildMethodKey(service, methodName);
        Type[] reqClassList = getRequestCache().get(key);
        if (reqClassList == null) {
            //read interface and method from cache
            String interfaceClass = ConfigUniqueNameGenerator.getInterfaceName(service);
            Class clazz = ClassUtils.forName(interfaceClass, true);
            loadClassToCache(key, clazz, methodName);
        }
        return getRequestCache().get(key);
    }
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