Further information:
If you want to upload a pojo model defintion you need to add it to the WEB-INF/lib directory of gwt-console-server.war as well. If you don't, the console server application won't be able to deserialize the package (KnowledgePackageImpl) and will throw a RuntimeException which you won't see in the logs.
The only result is going to be a console with empty process definition list.