问Protobuf自定义选项在protojson库生成的JSON中没有显示

EN

func main() {
    protogen.Options{
    }.Run(func(gen *protogen.Plugin) error {

        gen.SupportedFeatures = uint64(pluginpb.CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL)

        // The type information for all extensions is in the source files,
        // so we need to extract them into a dynamically created protoregistry.Types.
        extTypes := new(protoregistry.Types)
        for _, file := range gen.Files {
            if err := registerAllExtensions(extTypes, file.Desc); err != nil {
                panic(err)
            }
        }

        // run through the files again, extracting and printing the Message options
        for _, sourceFile := range gen.Files {
            if !sourceFile.Generate {
                continue
            }

            // setup output file
            outputfile := gen.NewGeneratedFile("./out.txt", sourceFile.GoImportPath)

            for _, message := range sourceFile.Messages {
                outputfile.P(fmt.Sprintf("\nMessage %s:", message.Desc.Name()))

                // The MessageOptions as provided by protoc does not know about
                // dynamically created extensions, so they are left as unknown fields.
                // We round-trip marshal and unmarshal the options with
                // a dynamically created resolver that does know about extensions at runtime.
                options := message.Desc.Options().(*descriptorpb.MessageOptions)
                b, err := proto.Marshal(options)
                if err != nil {
                    panic(err)
                }
                options.Reset()
                err = proto.UnmarshalOptions{Resolver: extTypes}.Unmarshal(b, options)
                if err != nil {
                    panic(err)
                }

                // Use protobuf reflection to iterate over all the extension fields,
                // looking for the ones that we are interested in.
                options.ProtoReflect().Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
                    if !fd.IsExtension() {
                        return true
                    }

                    outputfile.P(fmt.Sprintf("Value of option %s is %s",fd.Name(), v.String()))

                    // Make use of fd and v based on their reflective properties.

                    return true
                })
            }
        }
        
        return nil
    })
}

// Recursively register all extensions into the provided protoregistry.Types,
// starting with the protoreflect.FileDescriptor and recursing into its MessageDescriptors,
// their nested MessageDescriptors, and so on.
//
// This leverages the fact that both protoreflect.FileDescriptor and protoreflect.MessageDescriptor 
// have identical Messages() and Extensions() functions in order to recurse through a single function
func registerAllExtensions(extTypes *protoregistry.Types, descs interface {
    Messages() protoreflect.MessageDescriptors
    Extensions() protoreflect.ExtensionDescriptors
}) error {
    mds := descs.Messages()
    for i := 0; i < mds.Len(); i++ {
        registerAllExtensions(extTypes, mds.Get(i))
    }
    xds := descs.Extensions()
    for i := 0; i < xds.Len(); i++ {
        if err := extTypes.RegisterExtension(dynamicpb.NewExtensionType(xds.Get(i))); err != nil {
            return err
        }
    }
    return nil
}