You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: blackhole.go
    path of file: ./repos/v2ray-core/infra/conf
    
    the code of the file until where you have to start completion: package conf

import (
	"encoding/json"

	"github.com/golang/protobuf/proto"

	"v2ray.com/core/common/serial"
	"v2ray.com/core/proxy/blackhole"
)

type NoneResponse struct{}

func (*NoneResponse) Build() (proto.Message, error) {
	return new(blackhole.NoneResponse), nil
}

type 
    
func (v *BlackholeConfig) Build() (proto.Message, error) {
	config := new(blackhole.Config)
	if v.Response != nil {
		response, _, err := configLoader.Load(v.Response)
		if err != nil {
			return nil, newError("Config: Failed to parse Blackhole response config.").Base(err)
		}
		responseSettings, err := response.(Buildable).Build()
		if err != nil {
			return nil, err
		}
		config.Response = serial.ToTypedMessage(responseSettings)
	}

	return config, nil
}