Snapshots of proxied APT repositories are missing metadata

[robleady]

I'm attempting to use a snapshot of the upstream Debian APT repositories as part of our build process.
This is failing as not all of the required metadata files are being copied into the snapshots directory structure, in particular the Release file is missing underneath binary-amd64

which results in this error during an installation of Debian 11 that is using Nexus as its mirror:

In the request.log I see the following entries, showing a 404 for the Release file under binary-amd64.

x.x.x.x - - [16/Oct/2023:21:30:08 +0100] "GET /repository/bullseye/snapshots/20231016/dists/bullseye/Release HTTP/1.1" 200 - 113489 15 "Wget/1.21" [qtp914303347-8260]
x.x.x.x - - [16/Oct/2023:21:30:08 +0100] "GET /repository/bullseye/snapshots/20231016/dists/oldstable/Release HTTP/1.1" 404 - 1582 0 "Wget/1.21" [qtp914303347-7984]
x.x.x.x - - [16/Oct/2023:21:30:08 +0100] "GET /repository/bullseye/snapshots/20231016/dists/bullseye/main/binary-amd64/Release HTTP/1.1" 404 - 1624 0 "Wget/1.21" [qtp914303347-8246]

• Do you have a workaround you are using at present?
  No

• What feature or behavior is this required for?
  Snapshots of APT repositories

• How could we solve this issue? (Not knowing is okay!)
  Ideally, all files under the metadata tree should be copied into a snapshot.

• Tell us about your Nexus Repository deployment: what version, operating system, and database are you using?
  Nexus OSS 3.56.0-01 running on Windows

This is potentially related to this other issue: #230