public T routeNode(String objectKey) {
        if (ring.isEmpty()) {
            return null;
        }
        Long hashVal = hashFunction.hash(objectKey);
        SortedMap<Long, VirtualNode<T>> tailMap = ring.tailMap(hashVal);
        Long nodeHashVal = !tailMap.isEmpty() ? tailMap.firstKey() : ring.firstKey();
        return ring.get(nodeHashVal).getPhysicalNode();
    }
with a specified key, route the nearest Node instance in the current hash ring
@param objectKey the object key to find a nearest Node
@return
core/src/main/java/thirdparty/com/github/jaskey/consistenthash/ConsistentHashRouter.java