@Deprecated public interface PacketExtension extends ExtensionElement
An extension element is an XML subdocument with a root element name and namespace. Extension elements are used to provide extended functionality beyond what is in the base XMPP specification. Examples of extensions elements include message events, message properties, and extra presence data. IQ stanzas have limited support for extension elements.
This class is used primarily for extended content in XMPP Stanzas, to act as so called "extension elements". For more information see RFC 6120 § 8.4 Extended Content.