If a process is started with a business key, there doesn't seem to be an easy way to retrieve the business key from a task listener (i.e. from the TaskListener.notify(DelegateTask delegateTask); or JavaDelegate.execute(DelegateExecution delegateExecution); functions)
Currently it looks like the workaround is to just put the business key in the variables map.
If there was a way to do
that'd be great.