Cancel the execution of this task. No-op if invoked after the task was already executed.
@return the deadline at which the handler associated with the scheduled task should be delivered a {@link Type#TIMER_TASK} event.
@return the reactor that created this task.
Represents work scheduled with a {@link Reactor} for execution at some point in the future. <p> Tasks are created using the {@link Reactor#schedule(int, Handler)} method.