public void addSummaryFeatures(FeatureList features) {
        if (summaryFeatures == null)
            summaryFeatures = new LinkedHashSet<>();
        for (ReferenceNode feature : features) {
            summaryFeatures.add(feature);
        }
    }
Adds the content of the given feature list to the internal list of summary features.
config-model/src/main/java/com/yahoo/schema/RankProfile.java