JAXB and Inheritance - EclipseLink MOXy's @XmlClassExtractor

In a previous post I covered how JAXB's XmlAdapter could be leveraged to use a node unique to the subtype as the inheritance indicator.  In this post I'll demonstrate that if that node is an XML attribute, then EclipseLink JAXB (MOXy)'s @XmlClassExtractor could be leveraged to do the same thing in fewer lines of code.