Message events are supported by the current design tools, but they only generate a message reference inside the event. Can you support a Message artifact in order to generate the relevant BPMN element (i.e. the message that is referenced in the event)? I understand that visualizing the message is used more in choreography diagrams as part of a conversation, but it would be helpful to have a way to model the Message as a property (similar to a Data Object) so that it is part of the generated XML.
How do you support it today? Is the Message definition external to the process definition? If so, how are Message definitions loaded? Do you validate message refs in templates today? I had issues when trying to deploy templates using message events generated with your design tools (see related issues), so I was not sure.