Related docs plugin does not show suggestions

The related docs plugin does not show any suggestions. Steps to reproduce:

• run the related docs demo project (2.08.00-SNAPSHOT)
• In the CMS, open the document 'relateddocsdemo/common/About Us'
• in the top bar, click 'edit'

Expected behavior: the 'suggestions' widget shown suggestions for related docs
Actual behavior: no suggestions are shown

• at the bottom, click 'refresh suggestions'

Expected behavior: the list of suggestions is refreshed
Actual behavior: still no suggestions are shown, and the following error is logged:

18.08.2011 11:45:18 WARN [org.apache.wicket.util.lang.Classes.resolveClass():92] Could not resolve class: int