private void renderSection(XMLWriter writer, HitGroup hit) {
        writer.openTag("section");
        writer.attribute("id", hit.getDisplayId());
        writer.attribute("layout", hit.getField("layout"));
        writer.attribute("region", hit.getField("region"));
        writer.attribute("placement", hit.getField("placement")); // deprecated in 5.0
        writer.closeStartTag();
        renderSectionContent(writer, hit);
    }
Writes a hit's default attributes like 'type', 'source', 'relevance'.
container-search/src/main/java/com/yahoo/search/pagetemplates/result/PageTemplatesXmlRenderer.java