_childCache.put(parent,childSet.toArray(NO_CHILDREN));
cache.put(parent,childSet.toArray(NO_CHILDREN));
    public void addUrl(HttpUrl url) {        Map map = new HashMap();        if (_urlProperties.get(url) != null) throw new IllegalStateException("Adding an URL that is already there " + url);        _urlProperties.put(url, map);                HttpUrl parent = url.getParentUrl();        SortedSet childSet;        if (url.getParameters() != null) {            childSet = (SortedSet) _urlQueries.get(parent);            if (childSet == null) {                childSet = new TreeSet();                _urlQueries.put(parent, childSet);            }        } else {            childSet = (SortedSet) _urlChildren.get(parent);            if (childSet == null) {                childSet = new TreeSet();                _urlChildren.put(parent, childSet);            }        }        childSet.add(url);        _childCache.put(parent,childSet.toArray(NO_CHILDREN));    }