flow-control-collectionsのエラー

ここのif文でエラー発生

  Map<String, dynamic> toMap({bool withId = false}) => {
        if (withId) 'uuid': uuid,
        'title': title,
      };

dart - flutter --flow-control-collections are needed, but are they? - Stack Overflow

のトリック使う

analysis_options.yaml

analyzer:
  enable-experiment:
    - control-flow-collections

pubspec.yml

environment:
  sdk: ">=2.5.2 <3.0.0"