anchor.diff:  /// Service extensions can be found in [service_extensions.dart].
   class _ServiceExtensionToggle extends _ServiceExtensionWidget {
     const _ServiceExtensionToggle({
  -    Key key,
  -    @required this.service,
  -    @required String Function(dynamic) describeError,
  +    Key? key,
  +    required this.service,
  +    required String Function(dynamic) describeError,
     }) : super(
             key: key,
             // Don't show messages on success or when this toggle is in progress.
  
positive.code: 
          final wasSelected = extensionState.isSelected;
  
          serviceManager.serviceExtensionManager.setServiceExtensionState(
            extensionState.description.extension,
            enabled: !wasSelected,
            value: wasSelected
  
negative.code: /// Service extensions can be found in [service_extensions.dart].
  class ServiceExtensionCheckbox extends _ServiceExtensionWidget {
    ServiceExtensionCheckbox({
      Key? key,
      required this.service,
    }) : super(
            key: key,
            // Don't show messages on success or when this toggle is in progress.
  