class EventQueryParams extends DataQueryParams {

    public Set<Legend> getItemLegends()
    {
        return getItemsAndItemFilters().stream()
            .filter( QueryItem::hasLegendSet )
            .map( i -> i.getLegendSet().getLegends() )
            .flatMap( i -> i.stream() )
            .collect( Collectors.toSet() );
    }

    private  EventQueryParams();

}