Using java.net.URL in Set-s and Map-s is a no-no. Wicket should use java.net.URI instead. See [1] for an example.
Attila [1] "More Joy of Sets" example with URL from Google Tech Talks: http://www.youtube.com/watch?v=wDN_EYUvUq0#t=9m58s 2011/7/3 Bertrand Guay-Paquet <ber...@step.polymtl.ca> > > > When I said "second set", I meant that the same URLs are added, which is > indeed strange considering that they are added to a HashSet! > > After more digging, I found that the URLs are not in fact equal as > determined by URL.equals(). The URLs with the same string value differ in > their "host" property which is used by URL.equals(). One "set" of URLs has a > host == null and the other has host == "". The actual host comparison is > done in URLStreamHandler.hostsEqual(). > >