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: transport_authenticators.go
    path of file: ./repos/v2ray-core/infra/conf
    
    the code of the file until where you have to start completion: package conf

import (
	"sort"

	"github.com/golang/protobuf/proto"

	"v2ray.com/core/transport/internet/headers/http"
	"v2ray.com/core/transport/internet/headers/noop"
	"v2ray.com/core/transport/internet/headers/srtp"
	"v2ray.com/core/transport/internet/headers/tls"
	"v2ray.com/core/transport/internet/headers/utp"
	"v2ray.com/core/transport/internet/headers/wechat"
	"v2ray.com/core/transport/internet/headers/wireguard"
)

type NoOpAuthenticator struct{}

func (NoOpAuthenticator) Build() (proto.Message, error) {
	return new(noop.Config), nil
}

type NoOpConnectionAuthenticator struct{}

func (NoOpConnectionAuthenticator) Build() (proto.Message, error) {
	return new(noop.ConnectionConfig), nil
}

type SRTPAuthenticator struct{}

func (SRTPAuthenticator) Build() (proto.Message, error)
    
func (v *HTTPAuthenticatorRequest) Build() (*http.RequestConfig, error) {
	config := &http.RequestConfig{
		Uri: []string{"/"},
		Header: []*http.Header{
			{
				Name:  "Host",
				Value: []string{"www.baidu.com", "www.bing.com"},
			},
			{
				Name: "User-Agent",
				Value: []string{
					"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36",
					"Mozilla/5.0 (iPhone; CPU iPhone OS 10_0_2 like Mac OS X) AppleWebKit/601.1 (KHTML, like Gecko) CriOS/53.0.2785.109 Mobile/14A456 Safari/601.1.46",
				},
			},
			{
				Name:  "Accept-Encoding",
				Value: []string{"gzip, deflate"},
			},
			{
				Name:  "Connection",
				Value: []string{"keep-alive"},
			},
			{
				Name:  "Pragma",
				Value: []string{"no-cache"},
			},
		},
	}

	if len(v.Version) > 0 {
		config.Version = &http.Version{Value: v.Version}
	}

	if len(v.Method) > 0 {
		config.Method = &http.Method{Value: v.Method}
	}

	if len(v.Path) > 0 {
		config.Uri = append([]string(nil), (v.Path)...)
	}

	if len(v.Headers) > 0 {
		config.Header = make([]*http.Header, 0, len(v.Headers))
		headerNames := sortMapKeys(v.Headers)
		for _, key := range headerNames {
			value := v.Headers[key]
			if value == nil {
				return nil, newError("empty HTTP header value: " + key).AtError()
			}
			config.Header = append(config.Header, &http.Header{
				Name:  key,
				Value: append([]string(nil), (*value)...),
			})
		}
	}

	return config, nil
}