Golang Net / http / transport Proxy CONNECT方法标头支持

Golang's package net/http/transport can automatic setup Proxy-Authorization header in

func (t *Transport) dialConn(ctx context.Context, cm connectMethod) (*persistConn, error)

like

proxyURL, _ := url.Parse("http://username:password@example.com")
client      := http.Client{Transport: &http.Transport{Proxy:http.ProxyURL(proxyURL)}}

But I need submit X-Header to proxy server. How Can I custom transport CONNECT method request header?

net/http/transport

how about this:

// ...
request, err := http.NewRequest("GET", "https://www.google.com", nil)
if err != nil {
  // do something
}
// add header here.
request.Header.Add("X-Header", "xxx")

response, err := client.Do(request)
if err != nil {
  // do something
}
// ...