private void queryContext(XMLWriter writer, Query owner) {
        if (owner.getTrace().getLevel()!=0) {
            XMLWriter xmlWriter=XMLWriter.from(writer);
            xmlWriter.openTag("meta").attribute("type", QueryContext.ID);
            TraceNode traceRoot = owner.getModel().getExecution().trace().traceNode().root();
            traceRoot.accept(new XmlRenderer.RenderingVisitor(xmlWriter, owner.getStartTime()));
            xmlWriter.closeTag();
        }
    }
Creates a json renderer using a custom executor.
Using a custom executor is useful for tests to avoid creating new threads for each renderer registry.
container-search/src/main/java/com/yahoo/search/pagetemplates/result/PageTemplatesXmlRenderer.java