@Override
public Cursor query(Filter filter, NodeState root) {
NodeBuilder builder = new ReadOnlyBuilder(root);
for (String name : elements(index.getPath())) {
builder = builder.child(name);
}
if (!builder.hasChildNode(INDEX_DATA_CHILD_NAME)) {
// index not initialized yet
return Cursors.newPathCursor(Collections.<String> emptySet());
}