This is my mistake in writing the 2.1.3 documentation. Seems I documented a feature that went into the 2.2.0 release, and is also scheduled for the 2.1.4 bug fix release (not yet released). The VersionedPortletApplicationManager was not yet available in 2.1.3.
The documentation covers the work done after the 2.1.4 release which you can find here in prereleased state:
I have attached the java file, you might want to try compiling and seeing if it works in 2.1.3
Apologies for the misleading documentation, got ahead of myself