public void prepare() {
        rankFeatures.prepare(rankProperties);
        matchPhase.prepare(rankProperties);
        secondPhase.prepare(rankProperties);
        matching.prepare(rankProperties);
        softTimeout.prepare(rankProperties);
        prepareNow(freshness);
        if (rerankCount != null)
            rankProperties.put("vespa.hitcollector.heapsize", rerankCount);
        if (keepRankCount != null)
            rankProperties.put("vespa.hitcollector.arraysize", keepRankCount);
        if (rankScoreDropLimit != null)
            rankProperties.put("vespa.hitcollector.rankscoredroplimit", rankScoreDropLimit);
    }
Sets sorting from a string. See {@link Sorting} on syntax
container-search/src/main/java/com/yahoo/search/query/Ranking.java