A DESCRIPTION OF THE PROBLEM :
Exampe 1 defines an abstract class Task that should be annotated with @XmlSeeAll but isn't. The example as given doesn't work.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
In example 1, the ant example should read:

    @XmlSeeAlso({JarTask.class,JavacTask.class})
    abstract class Task {
    }

at least, I had to do that to get it working and stack overflow agrees, thanks to Jared Brothers @ Google for finding this.
ACTUAL -
Currently reads:

    abstract class Task {
    }


URL OF FAULTY DOCUMENTATION :
http://docs.oracle.com/javase/7/docs/api/javax/xml/bind/annotation/XmlElementRef.html