[Analyzer] Lint avoid_classes_with_only_static_members is not working as intended

[Giuspepe]

The lint avoid_classes_with_only_static_members does not work if a class has only static methods.
If I run flutter analyze on a file with the example from https://dart-lang.github.io/linter/lints/avoid_classes_with_only_static_members.html, the lint avoid_classes_with_only_static_members is not triggered:

class DateUtils {
  static DateTime mostRecent(List<DateTime> dates) {
    return dates.reduce((a, b) => a.isAfter(b) ? a : b);
  }
}

However, if I add a static property to the class, the lint triggers as intended.

class DateUtils {
  static int i = 123;
  static DateTime mostRecent(List<DateTime> dates) {
    return dates.reduce((a, b) => a.isAfter(b) ? a : b);
  }
}

I'm on MacOS and my Dart version is 2.13.1 (stable).