private void markSubquery(int begin, int end, long subqueryBitmap) {
        if (visited[begin]) {
            visited[end] = true;
            subqueryMarkers[end] |= subqueryBitmap;
        }
    }
Returns the end value of the interval,
or -1 if the highest end value seen is less than the interval begin.
predicate-search/src/main/java/com/yahoo/search/predicate/index/PredicateSearch.java