toXml method
Implementation
@override
void toXml(XmlBuilder context, NamespaceManager nsmgr) {
  const davns = kDavNamespaceUrlStr;
  nsmgr.generate(davns);
  context.element(
    WebDavElementNames.propfind,
    namespace: davns,
    namespaces: Map.fromEntries(nsmgr.all),
    nest: () {
      context.element(WebDavElementNames.propname, namespace: davns);
    },
  );
}