Handle_response can't use placeholder?

[libla]

1. Caddy version (caddy version):

v2.4.6 h1:HGkGICFGvyrodcqOOclHKfvJC0qTU7vny/7FhYp9hNw=

2. How I run Caddy:

a. System environment:

Debian 10.2, Docker version 20.10.10, build b485636

b. Command:

caddy run

c. Service/unit/compose file:

docker run --name caddy --net=host -e TZ=Asia/Shanghai -e GO111MODULE=on -e GOPROXY=https://goproxy.cn,direct --restart=always -v /data/www:/data/www:ro -v /etc/caddy:/etc/caddy:ro -v /var/log/caddy:/log -w /etc/caddy -d caddy:builder-alpine sh -c "if [ ! -x /usr/bin/caddy ]; then xcaddy build --output /usr/bin/caddy --with github.com/caddyserver/format-encoder; fi; caddy run"

d. My complete Caddyfile or JSON config:

reverse_proxy http://127.0.0.1:3690 {
    header_down -Server
    header_down Location ^http:// {http.request.scheme}://
    header_down Refresh ^http:// {http.request.scheme}://
    transport http {
        keepalive 60s
    }
    @auth status 401
    handle_response @auth {
        header WWW-Authenticate {http.reverse_proxy.header.WWW-Authenticate}
        respond "" {http.reverse_proxy.status_code}
    }
}

3. The problem I’m having:

curl -v "http://localhost/test"
*   Trying 82.157.162.166...
* TCP_NODELAY set
* Connected to localhost (::1) port 80 (#0)
> GET /test HTTP/1.1
> Host: localhost
> User-Agent: curl/7.59.0
> Accept: */*
>
< HTTP/1.1 401 Unauthorized
< Server: nginx
< Www-Authenticate:
< Date: Fri, 19 Nov 2021 03:18:04 GMT
< Content-Length: 0
<
* Connection #0 to host localhost left intact

I use caddy to reverse proxy apache svn server, and hide the return information of apache.
But Www-Authenticate in headers is empty.

4. Error messages and/or full log output:

5. What I already tried:

I change respond to

respond {http.reverse_proxy.header.WWW-Authenticate} {http.reverse_proxy.status_code} 

or

respond {http.reverse_proxy.header.Host} {http.reverse_proxy.status_code} 

will return original text , not the corresponding value of the placeholder.

6. Links to relevant resources:

[matt (Matt Holt)]

Hmm, you might need to use the canonical casing of HTTP/1.1 header fields: {http.reverse_proxy.header.Www-Authenticate} - does that work?

[libla]

This field can work correctly.
thanks!