public Collection<SourceGroup> groups() {
        List<SourceGroup> result = new ArrayList<>();
        for (ComponentAdaptor<SourceGroup> group :
                sourceGroups.allComponents()) {
            result.add(group.model);
        }
        return result;
    }
Owns all the source groups in the search chains model.
@author Tony Vaagenes
config-model/src/main/java/com/yahoo/vespa/model/container/search/searchchain/SourceGroupRegistry.java