@Override
    protected List<Class<? extends Throwable>> getRetriableExceptions() {
        return retriable;
    }
@return true if the Throwable has one of the following exception type as a cause: 
{@link SocketException}, {@link SocketTimeoutException}
ribbon-httpclient/src/main/java/com/netflix/niws/client/http/HttpClientLoadBalancerErrorHandler.java