Attempts to cancel execution of this task.
Attempts to cancel execution of this task. This attempt will
fail if the task has already completed, has already been cancelled,
or could not be cancelled for some other reason. If successful,
and this task has not started when cancel is called,
this task should never run. If the task has already started,
then the mayInterruptIfRunning parameter determines
whether the thread executing this task should be interrupted in
an attempt to stop the task.
If this method returns true, the future should never complete.
{ @code true} if the thread executing this task should be interrupted; otherwise, in-progress tasks are allowed to complete
{ @code false} if the task could not be cancelled, typically because it has already completed normally; { @code true} otherwise
Wraps a future, adding a method to cancel it
return type of Future