2.84.0
(feat): Object types with XML encoding metadata (e.g. TwiML) now implement IXmlNode with ToXml()/ToXElement(),
static FromXml(string)/FromXElement(XElement) parsers, and fluent child builder methods
(response.Say("Hello", voice: "man").Dial(...)). Unknown attributes and child elements are preserved in
AdditionalAttributes/AdditionalChildren and re-emitted; AddChild(XmlElement) adds arbitrary elements.
Parsing rejects malformed XML, mismatched root elements and DTDs. Types without XML metadata are unchanged.