Private Repositories and Public Mirrors URL link

I have repositories locally on my BitBucket Server and mirrored on GitHub. I have the following refs:
* `origin` so that the command `git config --get remote.origin.url` returns `ssh://bitbucket/netfw/RJCP.DLL.SerialPortStream.git`. Note, that the SSH configuration (`.ssh/config`) I use maps the keyword `bitbucket` to the correct host name.
* `github` points to `git@github.com:jcurl/SerialPortStream.git`

I am trying to create using SourceLink a PDB that maps to github, not to my local (private) repository. On releases of my OSS packages I push to GitHub. I can't seem to get it to work, read various docs in the repository, tried to understand the implementation targets.

With:
```xml

https://github.com/jcurl/RJCP.DLL.SerialPortStream
$(RepositoryUrl)
true
true
true
snupkg

embedded
true
true
true

```

I confirm that the NuPacket repository URL is https://github.com, and the PDBs point correctly to my own internal webserver hosting my code.

If I use instead `Microsoft.SourceLink.GitHub`, how do I get the source links to point to the URLs `https://raw.githubusercontent.com/jcurl/SerialPortStream`, instead of `https://raw.githubusercontent.com/netfw/RJCP.DLL.SerialPortStream`? I couldn't figure out either how to use the advanced options of ``, or in which `Target` to define that in, if that is even the correct place?