You usually should send an object that will represent the event that you are signalling. I usually send something more representative like an object that represent the event and in the case that you need to send a map of parameter you should create an object to wrap that map and add more semantic meaning to the event. You can take a look at the emergency services application to see how we are sending events and how we are using that information in different activities of the process.
https://github.com/Salaboy/emergency-service-drools-app
Best Regards