anchor.diff:  // WidgetInspectorService show up as in scope as far as the analysis server is
   // concerned.
   extension WidgetInspectorServicePrivateMethods on WidgetInspectorService {
  -  Map<String, Object /*?*/ > /*?*/ _nodeToJson(
  -    DiagnosticsNode /*?*/ node,
  +  Map<String, Object?>? _nodeToJson(
  +    DiagnosticsNode? node,
       InspectorSerializationDelegate delegate,
     ) {
       throw 'Dummy extension method to make the code type check when it calls private members';
  
positive.code: // widget_inspector.dart library so using protected members is fine.
  // ignore_for_file: invalid_use_of_visible_for_testing_member
  // ignore_for_file: invalid_use_of_protected_member
  
  // This annotation should stay here for compatibility with legacy code.
  // @dart=2.9
  
  import 'dart:async';
  import 'dart:convert';
  
negative.code:     final groupName = parameters['groupName'];
  
      final result = instance._nodeToJson(
        WidgetsBinding.instance.renderViewElement?.toDiagnosticsNode(),
        InspectorSerializationDelegate(
          groupName: groupName,
          subtreeDepth: 1000000,
  