The artefacts list can contain either handler classes (as above) or instances of handlers.

So, what does an artefact handler look like? Well, put simply it is an implementation of the interface. To make life a bit easier, there is a skeleton implementation that can readily be extended: ArtefactHandlerAdapter.

The best way to understand how both the handler and wrapper classes work is to look at the Quartz plugin:

Another example is the which adds a realm artefact.