@Override
    public void process(boolean validate, boolean documentsOnly) {
        if (documentsOnly) return;

        for (SDField f : schema.allConcreteFields()) {
            if (f.getRanking().isFilter()) {
                filterField(f.getName());
            }
        }

        for (RankProfile profile : rankProfileRegistry.rankProfilesOf(schema)) {
            Set<String> filterFields = new LinkedHashSet<>();
            findFilterFields(schema, profile, filterFields);
            for (Iterator<String> itr = filterFields.iterator(); itr.hasNext(); ) {
                String fieldName = itr.next();
                profile.filterFields().add(fieldName);
                profile.addRankSetting(fieldName, RankProfile.RankSetting.Type.RANKTYPE, RankType.EMPTY);
            }
        }
    }
Takes the fields and indexes that are of type rank filter, and stores those names on all rank profiles

@author Vegard Havdal
config-model/src/main/java/com/yahoo/schema/processing/FilterFieldNames.java