anchor.diff:  /// will be the entry point to the plugin's native code.
   class IOSPlugin extends PluginPlatform {
     const IOSPlugin({
  -    @required this.name,
  -    this.classPrefix,
  -    @required this.pluginClass,
  +    required this.name,
  +    required this.classPrefix,
  +    required this.pluginClass,
     });
   
     factory IOSPlugin.fromYaml(String name, YamlMap yaml) {
  
positive.code:   static const String kConfigKey = 'macos';
  
    final String name;
    final String pluginClass;
    final String dartPluginClass;
  
    @override
    bool isNative() => pluginClass != null;
  
negative.code:   static const String kConfigKey = 'linux';
  
    final String name;
    final String? pluginClass;
    final String? dartPluginClass;
  
    @override
    bool isNative() => pluginClass != null;
  