Does so by introducing TaskListener which is just like ActionListener but
gets the Task as each parameter. Unlike ActionListener which is used
_everywhere_ you can only use TaskListener directly with TransportAction.
TransportAction under the covers uses an ActionListener implemetation that
closes over the task to call the TaskListener.
It defaults to false and when false it returns a task identifier. Right
now all you can do is get the task to see if it is still running. Once
the task finishes it vanishes and you can't get any information about it.
This creates an reindex plugin with a very basic implementation that is
very like delete-by-query. New we'll integrate it with the task managament
work but for now this works.
Nik Everett