@Override
    public void setIndexName(String index) {
        String toSet = (index == null) ? "" : index;
        super.setIndexName(toSet);
        this.index = toSet;
    }
Sets the default index name to apply to all child items of this.
This is useful in conjunction with using {@link PureWeightedItem}s as children.
container-search/src/main/java/com/yahoo/prelude/query/WeakAndItem.java