`Directive` generate redundant '`' in `DirectiveType.part` type

[KuiyuanFu]

I am test meta conding, i want generate a part of XXX; code, i try to use b.directives.add(Directive.partOf(entryLib.name)); to do this, but i get part of 'test';, the ' is redundant.

class JsonSerializableBuilder implements Builder {
  static const inputExtension = '.dart';
  static const ouputExtension = '.json.dart';

  @override
  final buildExtensions = const {
    inputExtension: [ouputExtension]
  };

  @override
  Future<void> build(BuildStep buildStep) async {

    final entryLib = await buildStep.inputLibrary;

   // entryLib.name is 'test'
    final jsonLibrary = Library((b) {
      b.directives.add(Directive.partOf(entryLib.name));
    });

    final emitter = DartEmitter.scoped(
        orderDirectives: true, useNullSafetySyntax: sourceLibIsNonNullable);
    final rawOutput = jsonLibrary.accept(emitter).toString();

    final jsonLibraryContent = DartFormatter().format(rawOutput);

    final jsonLibraryAsset = buildStep.inputId.changeExtension(ouputExtension);

    await buildStep.writeAsString(jsonLibraryAsset, jsonLibraryContent);
  }
}

The generated file is

part of 'test';

I find code in code_builder-4.1.0\lib\src\emitter.dart 323 lines. The code not consider DirectiveType, use ' to all type. I think it is a bug........

  @override
  StringSink visitDirective(Directive spec, [StringSink? output]) {
    output ??= StringBuffer();
....
    output.write("'${spec.url}'");
....
    return output;
  }

[KuiyuanFu]

emmm my fault