(As mentioned in Bug 5267 comment #3.)

In the XQuery spec,
    section 2.5.1 Predefined Schema Types, point 5
and
    Appendix H Glossary, under xs:anyAtomicType
both say:

    All primitive atomic types, such as xs:integer, xs:string,
    and xs:untypedAtomic, have xs:anyAtomicType as their base type.

but xs:integer is not a primitive atomic type. (And I don't think
xs:untypedAtomic is either, but that's a tricker case.)

You could just use different examples, e.g. xs:decimal and xs:dateTime.