public async Task <IEnumerable <Course> > GetCoursesByIdAsync( [ID(nameof(Course))] Guid[] ids, CourseByIdDataLoader courseByIdDataLoader, CancellationToken cancellationToken) => await courseByIdDataLoader.LoadAsync(ids, cancellationToken) ?? Array.Empty <Course>();
public Task <Course?> GetCourseByIdAsync( [ID(nameof(Course))] Guid id, CourseByIdDataLoader courseByIdDataLoader, CancellationToken cancellationToken) => courseByIdDataLoader.LoadAsync(id, cancellationToken) !;