AdvantageAttributes..::..Extensions Property

Side-channel for feature extensions that need structured XML alongside the attribute bag. Multiple features coexist by claiming distinct element names (e.g. LocalizedSlots for the localization layer). Core treats the child elements as opaque XML — feature libraries own parse/emit via GetExtension(String) / SetExtension(String, XmlElement). Null when no extensions are present — the wrapper element is omitted from the on-disk XML entirely.

[DataMemberAttribute]
public AdvantageAttributeExtensions Extensions { get; set; }