How to generate @entity using @freezed?

[ziehlke]

Hi all!
i'm using this example trying to generate an entity with @freezed annotation.
I added the neccessary dependencies to pubspec.yml and modified the Task class as follow

import 'package:freezed_annotation/freezed_annotation.dart';
import 'package:floor/floor.dart';

part 'task.freezed.dart';

@freezed
class Task with _$Task {
  @entity
  factory Task(
    @PrimaryKey(autoGenerate: true)
    int? id,
    String message,
  ) = _Task;
}

the output I get is: There are no entities added to the database annotation.
what am I missing here, please?