static private boolean isSingleRawBoolOrReferenceAttribute(AttributesConfig.Attribute attribute) {
        var datatype = attribute.datatype();
        return  (datatype == AttributesConfig.Attribute.Datatype.RAW ||
                datatype == AttributesConfig.Attribute.Datatype.BOOL ||
                datatype == AttributesConfig.Attribute.Datatype.REFERENCE) &&
                attribute.collectiontype() == AttributesConfig.Attribute.Collectiontype.SINGLE;
    }
Constructs a new instance of this searcher with the given component id and config.

@param clusterConfig The config for the cluster that this searcher is deployed for.
container-search/src/main/java/com/yahoo/search/grouping/GroupingValidator.java