Hello Mark,
the interfaces for observer support are only generated for outgoing events. If you have no outgoing events in your statechart the observer support is not generated.
There is a bug in the current release, which thereby shows that if an event has no type specified, the generated code can not be compiled. This bug is already fixed
and the fix will be included in the next release. As a workaround set the type of outgoing events to 'void'.
Regards
Markus