我正在尝试迁移 dart null safety，但运行时出现以下错误dart migrate
Bad state: Error: package has unmigrated dependencies.\n\nBefore migrating your package, we recommend ensuring that every library it\nimports (either directly or indirectly) has been migrated to null safety, so\nthat you will be able to run your unit tests in sound null checking mode. You\nare currently importing the following non-null-safe libraries:\n\n file:///C:/flutter/packages/flutter_tools/test/integration.shard/test_data/basic_project.dart\n file:///C:/flutter/packages/flutter_tools/test/integration.shard/test_data/deferred_components_config.dart\n file:///C:/flutter/packages/flutter_tools/test/integration.shard/test_data/project.dart\n file:///C:/flutter/packages/flutter_tools/test/integration.shard/test_driver.dart\n file:///C:/flutter/packages/flutter_tools/test/src/test_flutter_command_runner.dart\n file:///C:/flutter/packages/flutter_tools/test/src/testbed.dart\n package:dwds/data/build_result.dart\n package:dwds/data/connect_request.dart\n package:dwds/data/debug_event.dart\n package:dwds/data/devtools_request.dart\n package:dwds/data/error_response.dart\n package:dwds/data/extension_request.dart\n package:dwds/data/isolate_events.dart\n package:dwds/data/register_event.dart\n package:dwds/src/debugging/dart_scope.dart\n package:dwds/src/debugging/debugger.dart\n package:dwds/src/debugging/execution_context.dart\n package:dwds/src/debugging/frame_computer.dart\n package:dwds/src/debugging/inspector.dart\n package:dwds/src/debugging/instance.dart\n package:dwds/src/debugging/libraries.dart\n package:dwds/src/debugging/location.dart\n package:dwds/src/debugging/metadata/class.dart\n package:dwds/src/debugging/metadata/function.dart\n …我有一个像这样的简单课程：
class Restaurant{
final String id;
final String name;
List<Serving> servingList;
Restaurant({
required this.id,
required this.name,
this.servingList = [], // ERROR
});
}
默认情况下，我想要一个空列表servingList，并稍后将对象添加到该列表中。但我收到错误消息The default value of an optional parameter must be constant.
我需要做什么？
我感谢每一个帮助，谢谢！