f.feedz.io nuget feed is not supported

Description:

When setting up a remote Nuget repository pointing to https://f.feedz.io/elastic/all/nuget and attempting to install a package that exists in the index file, Artifactory executes a request to find the file, but since it attempts to look for its metadata in a different structure, it fails to find it with a 404. 

The request to install the elastic.apm version 1.5.1 package, for example, will result in the following request:

https://f.feedz.io/elastic/all/nuget/v3/registration-gz-semver2/elastic.apm/1.5.1.json

Which will result in 404:

2022-04-27T12:13:13.043Z [jfrt ] [ERROR] [59f517e219b98c9d] [etV3VirtualAndRemoteCommon:275] [http-nio-8081-exec-7] - Failed to download resource in repo: dev-nuget-remote, at url: https://f.feedz.io/elastic/all/nuget/v3/registration-gz-semver2/elastic.apm/1.5.1.json. HTTP STATUS CODE: 404

This package’s location on the https://f.feedz.io/elastic/all/nuget/v3/registration-gz-semver2/elastic.apm/index.json is:

https://f.feedz.io/elastic/all/nuget/v3/registration-gz-semver2/elastic.apm/1.5.1/index.json

Attempting to install the same package via the nuget gallery is successful and the request looks like this (found in https://api.nuget.org/v3/registration5-gz-semver2/elastic.apm/index.json):

https://api.nuget.org/v3/registration5-gz-semver2/elastic.apm/1.5.1.json

Comparing the two, it appears that Artifactory is attempting to look for this package in feedz.io in the format of elastic.apm/1.5.1.json (like it does in the nuget gallery) instead of searching for elastic.apm/1.5.1/index.json. 

*This will not work in V2 or V3

Impact:

This behavior makes this feed not usable with Artifactory.

Expected behavior:

Artifactory should be able to handle and translate irregular registration repositories (that have a different structure than nuget gallery)

Steps to reproduce:

1. Create a remote nuget repository with the following configuration:
2. URL: https://f.feedz.io/elastic/all/nuget
3. Download Context Path: /packages
4. V3 feed URL: https://f.feedz.io/elastic/all/nuget/index.json

1. Point the nuget client to the repository with the V3 protocol
2. Attempt to install a package (the same package will be installed successfully directly from the feed r from nuget gallery)

Environment details:

Single node, version 7.37.14

Note: Part of the behavior is may be related to the fact that the Artifactory cannot handle the Published field outside of the <m:properties> tag, as described in RTFACT-26364.