Cannot retrieve information about a task within it's start event handler because task not initialised at the point the handler is invoked

Re-opens https://jira.jboss.org/browse/JBPM-2644 which, in my opinion, was incorrectly closed. See last few comments on this Jira for more info.
A common use-case (for us at least, and I suspect for many applications) is to perform some processing when a task starts in the start event handler. Currently, it is not possible to retrieve information about the task that has been started (in our case we need the participants) because it is not initialised when the start event fires.