LocalNotification constructor
      const
      LocalNotification({})
     
    
    
Implementation
const LocalNotification(
    {@required this.id,
    @required this.title,
    @required this.content,
    @required this.fireTime,
    this.buildId,
    this.extra,
    this.badge = 0,
    this.soundName,
    this.subtitle})
    : assert(id != null),
      assert(title != null),
      assert(content != null),
      assert(fireTime != null);