protected <S> S getProperty(IClientConfigKey<S> key, @Nullable IClientConfig requestConfig, S defaultValue) {
        if (requestConfig != null && requestConfig.get(key) != null) {
            return requestConfig.get(key);
        } else {
            return clientConfig.get(key, defaultValue);
        }
    }
Resolve the final property value from,
1. Request specific configuration
2. Default configuration
3. Default value

@param key
@param requestConfig
@param defaultValue
@return
ribbon-transport/src/main/java/com/netflix/ribbon/transport/netty/LoadBalancingRxClient.java