anchor.diff:  
     @override
     List<FieldElement> get fields {
  -    if (_fields == null) {
  -      if (linkedNode != null) {
  -        _resynthesizeMembers2();
  -      }
  -    }
  -    return _fields ?? const <FieldElement>[];
  +    if (!identical(_fields, _Sentinel.fieldElement)) {
  +      return _fields;
  +    }
  +
  +    if (linkedNode != null) {
  +      _resynthesizeMembers2();
  +    }
  +
  +    return _fields;
     }
   
     @override
  
positive.code: 
    @override
    List<ElementAnnotation> get metadata {
      if (_metadata != null) return _metadata!;
  
      if (linkedNode != null) {
        linkedContext!.applyResolution(linkedNode!);
  
negative.code: 
    @override
    List<TypeParameterElement> get typeParameters {
      if (!identical(_typeParameters, _Sentinel.typeParameterElement)) {
        return _typeParameters;
      }
  
      if (linkedNode != null) {
        var typeParameters = linkedContext!.getTypeParameters2(linkedNode!);
  