Apache basecontainer doesn't log basic auth username

The Apache basecontainer uses this logging config:

LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" \"%{X-Real-IP}i\"" openconext
CustomLog /proc/self/fd/1 openconext

The %u there should log the HTTP Basic username. However, that never happens.

For example, when querying Manage:

curl -u foo:bar -v  -X POST --json '{"ALL_ATTRIBUTES":true}' 'https://manage.acc.surfconext.nl/manage/api/internal/search/saml20_sp' -o /dev/null
[...]
> POST /manage/api/internal/search/saml20_sp HTTP/2
> Host: manage.acc.surfconext.nl
> authorization: Basic c3lzYWRtaW46Qlg1bHBpV0pUbUoycnpoQVo=
[...]
< HTTP/2 200
[...]

The log contains:

May 29 15:08:07 docker1.acc.ams.surfconext.nl managegui[773]: 145.100.191.4 - - [29/May/2026:15:08:06 +0200] "POST /manage/api/internal/search/saml20_sp HTTP/1.1" 200 12906216 "-" "curl/7.88.1" "145.100.183.8"

Locate the Apache basecontainer configuration containing the shown LogFormat and CustomLog directives, then reproduce the request with the provided curl command and inspect the container log. The work is done when an HTTP Basic-authenticated request logs its username in the %u field without losing the existing log fields.