found sort of a workaround by taking the action example from an empty process and copy it into the xml file directly.
Can you please post the workaround. I am also stuck on the same problem.
as i said, you have to edit the xml manually.
e.g. to add action to a transition, replace the () with lt/gt
(transition name="to_state" to="first")
(action name="action" class="com.sample.action.MessageActionHandler")
(message)Going to the first state!(/message)