anchor.diff:    }
   
     @override
  -  void visitLibraryDirective(LibraryDirective node) {
  -    checkComment(node.documentationComment);
  -  }
  -
  -  @override
     void visitMethodDeclaration(MethodDeclaration node) {
       checkComment(node.documentationComment);
     }
  
positive.code:   @override
    void visitClassTypeAlias(ClassTypeAlias node) {
      checkComment(node.documentationComment);
    }
  
    @override
  
negative.code:     final visitor = _Visitor(this);
      registry.addClassDeclaration(this, visitor);
      registry.addClassTypeAlias(this, visitor);
      registry.addCompilationUnit(this, visitor);
      registry.addConstructorDeclaration(this, visitor);
      registry.addEnumConstantDeclaration(this, visitor);
      registry.addEnumDeclaration(this, visitor);
  