>>>
class MummyMatchers {
  MummyMatchers([List<ResultPublisher> publishers]) : publishers = publishers !=
          null ? publishers : defaultPublishers.add(unittestPublisher);
}
<<<
class MummyMatchers {
  MummyMatchers([List<ResultPublisher> publishers])
      : publishers = publishers != null
            ? publishers
            : defaultPublishers.add(unittestPublisher);
}