How to define subclasses in flutter Isar database?

Question

I want to annotate my class that I wrote below to save in isar, but I don't know how...?

  class AppState {
     AppTimerState? appTimerState;
     TimedTaskIsarLog? appTimedTaskState;
     WorkIsarLog? appWorkState;
     AppState({
     this.appTimerState,
     this.appTimedTaskState,
     this.appWorkState,
       });
     static AppState? instance;

     static AppState getInstance() {
     instance ??= AppState();
     return instance!;
       }
  }