How to get a list of classes that have been loaded from out the jars in lib?

Is there a way to get an array of all the classes that have been loaded from out the library directory of cocoon2? In particlular I need all loaded subclasses of a specific interface foo.bar.Module that are in the .jar files (or where ever). The modules can be anywhere and in multiple .jar files that are not created by me so I cannot use a config file containing all the class names for my purpose. Thanks for your help, Jan.