Gianluca Pindinelli:
Well, specifying class loaders is a feature specific to each application server. If you compare the
Tomcat 5.5 documentation (where any class loader is valid) and the
Tomcat 6.0 documentation (where only specific class loaders inheriting from Tomcat's class loader are valid), you'll find that it's
technically not a bug, but rather intended behavior.
If you want to be able to use Liferay's portal-impl.jar classes in your plugins portlet, you'll have to figure out how to put Liferay 6.0 back onto Tomcat 5.5 (and lose any of the bugs or performance fixes that occurred between the Tomcat releases), since we no longer provide a bundle for it.