private static Recall optimizeIndexedItemByRestrict(SimpleIndexedItem item, String restrictParam) {
        if (!Hit.SDDOCNAME_FIELD.equals(item.getIndexName())) {
            return Recall.UNKNOWN_RECALL;
        }
        // a query term searching for sddocname will either recall everything or nothing, depending on whether
        // the term matches the restrict parameter or not
        return restrictParam.equals(item.getIndexedString())
               ? Recall.RECALLS_EVERYTHING
               : Recall.RECALLS_NOTHING;
    }
Replaces and {@link SimpleIndexedItem} searching in the {@link Hit#SDDOCNAME_FIELD} with an item
appropriate for the search node.
container-search/src/main/java/com/yahoo/prelude/querytransform/QueryRewrite.java