Access container from subdomain using https on apache

basically I have a docker container exposed on port 8080 and it already has his SSL certificate. I want to access that container using a subdomain without modifying the url and using that container certificate. The main domain already has his own certificate but I would like to use the docker container one. In otherwords, I would like users to use subdomain.example.com to access example.com:8080 using https but without letting them know of that redirect. I configured the virtual host like that:

<VirtualHost subdomain.example.com:443>
        ServerAdmin [email protected]
        ServerName subdomain.example.com
        ServerAlias subdomain.example.com
        ProxyRequests Off

        #ProxyPass / http://localhost:8080/
        <Location />
                ProxyPreserveHost On
                ProxyPass https://example.com:8080/
                ProxyPassReverse https:/example.com:8080/
        </Location>
     # Uncomment the line below if your site uses SSL.
     SSLProxyEngine On
</VirtualHost>

but I get an ERR_SSL_PROTOCOL_ERROR. Do you have any suggestion on how I could implement it?

The reason why it wasn't working is because I needed to create an SSL certificate for the subdomain (I used certbot to make it). The final configuration looks like this:

<VirtualHost subdomain.example.com:443>
        ServerAdmin [email protected]
        ServerName subdomain.example.com
        ServerAlias subdomain.example.com
        ProxyRequests Off

        #ProxyPass / http://localhost:8080/
        <Location />
                ProxyPreserveHost On
                ProxyPass https://example.com:8080/
                ProxyPassReverse https://example.com:8080/
        </Location>
        # Uncomment the line below if your site uses SSL.
        SSLProxyEngine On
        SSLCertificateFile /etc/letsencrypt/live/subdomain.example.com/fullchain.pem
        SSLCertificateKeyFile /etc/letsencrypt/live/subdomain.example.com/privkey.pem
        Include /etc/letsencrypt/options-ssl-apache.conf
</VirtualHost>