Thanks. I know.
But it still does not help me.
I need to send web service whenever the flow reaches human task.
So my solution was to take the same code as in CommandBasedWSHumanTaskHandler and add in execute method call to web service.
It will not help to use getTaskByPotentialOwner() since during the execute method the task is not saved in DB so I can't send the web service with the task id.. :((