golang http2 invalid Connection request header

test.go

package main

import (
	"fmt"
	"io"
	"net/http"
	"os"
	"time"
)

func main() {
	port := 8080
	http.HandleFunc("/", routeMatch)
	http.ListenAndServe(fmt.Sprintf("%s:%d", os.Getenv("HOST"), port), nil)
}

func routeMatch(w http.ResponseWriter, r *http.Request) {
	url := "https://http2.akamai.com/demo/" // this changes according to request
	var timeout int64 = 5
	fmt.Println(r.Header)
	resp, err := NewClient(url, r.Method, r.Header, timeout, r.Body, nil)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer resp.Body.Close()
	out := w.Header()
	for key, value := range resp.Header {
		out.Add(key, value[0])
	}
	w.WriteHeader(resp.StatusCode)
	io.Copy(w, resp.Body)
}

// NewClient is a http client and do a request
func NewClient(url string, method string, reqHeader http.Header, timeout int64, body io.Reader, transport *http.Transport) (*http.Response, error) {
	var client *http.Client
	if transport != nil {
		client = &http.Client{Timeout: time.Duration(timeout) * time.Second, Transport: transport}
	} else {
		client = &http.Client{Timeout: time.Duration(timeout) * time.Second}
	}
	req, err := http.NewRequest(method, url, body)
	if err != nil {
		return nil, err
	}
	req.Header = reqHeader
	return client.Do(req)
}