@Override
    public String toString() {
        StringBuffer ret = new StringBuffer();
        for (int i = 0; i < items.size(); ++i) {
            ret.append(items.get(i));
            if (i < items.size() - 1) {
                ret.append("/");
            }
        }
        return ret.toString();
    }
Normalizes the items list of this location so that all PREV or THIS locations are replaced by their actual
meaning. This carries some overhead since it is not done in place.

@return This, to allow chaining.
documentapi/src/main/java/com/yahoo/documentapi/messagebus/systemstate/rule/Location.java