Intialy raised as Bug in Kaamelot : http://developer.atlassian.com/jira/browse/KAAM-318.

In previous release, this function was defined as Default, and then addable systematically in new transition, but different issues was existing :

• The Post-Function had no default Event in argument
• The Post-Function was never added because overridden by the default Fire Event Function (see http://jira.atlassian.com/browse/JRA-25089).

Resolutions ;

• Generic Event has been defined as default Event,
• Weight has been changed in order not to be in conflict with weight of default Fire Event Function

and finally, is no more defined as default ... You will have to added it explicitly.