Hi Tobias,
I think the registerWorkItemHandler method accepts the name of the node itself, and not the type of node as specified in the javadoc. Therefore
I think your code should be (if you are registering the workItemHandler with the "Hello" node):
ksession.getWorkItemManager().registerWorkItemHandler("Hello", new MyOwnServiceHandler());
Or it might be that the javadoc refers to the name of the node as the type, or it might be a bug. But I think that should probably work.
Mare