expiresIn property
      
      Duration?
      get
      expiresIn
      
    
    
Returns a Duration until this task expires and is removed from the queue.
The returned Duration will be negative if this has expired.
Returns null if this task never expires.
Implementation
Duration? get expiresIn => (task.expire != null)
    ? triggerTime.add(task.expire!).difference(DateTime.now())
    : null;