private void renderGroup(XMLWriter writer, HitGroup hit) {
        writer.openTag(GROUP);
        renderHitAttributes(writer, hit);
        writer.closeStartTag();
    }
Writes a hit's default attributes like 'type', 'source', 'relevance'.
container-search/src/main/java/com/yahoo/search/pagetemplates/result/PageTemplatesXmlRenderer.java