r run.  If the task has already started,
 then the <code>mayInterruptIfRunning</code> parameter determines
 whether the thread executing this task should be interrupted in
 an attempt to stop the task.

 <p>After this method returns, subsequent calls to <code><a href="../../../../reference/java/util/concurrent/Future.html#isDone()">isDone()</a></code> will
 always return <code>true</code>.  Subsequent calls to <code><a href="../../../../reference/java/util/concurrent/Future.html#isCancelled()">isCancelled()