EventDataFilter only works for starting events which are dataOnly: false (the whole cloud event)

If user wants to filter the start event, currently they have to to add dataOnly:false to the event declaration and add a data:.data to take the data or, without adding dataOnly:false, use StateDataFilter.output (preferred alternative) rather than EventDataFilter

This should be fixed so EventDataFilter works also for dataOnly:true (which is the default)