Add 'PackageSourceMapping' entries to Nuget.config, since multiple sources are used

[Mark Schofield (mschofie)]

Description

When building the WindowsML samples through the command-line with:

.\build.cmd x64 Debug WindowsML

I see errors, along the lines of:

S:\source\github\microsoft\WindowsAppSDK-Samples\samples\WindowsML\cs\CSharpConsoleDesktop\CSharpConsoleDesktop\CSharpConsoleDesktop.csproj : error
 NU1507: There are 2 package sources defined in your configuration. When using central package management, please map your package sources with pac
kage source mapping (https://aka.ms/nuget-package-source-mapping) or specify a single package source. The following sources are defined: nuget.org,
 WinAppSDK-SampleDeps

The error is complaining because there's a :/Samples/nuget.config file with multiple packageSource elements, but no packageSourceMapping. So this PR adds packageSourceMapping for the packageSource elements.

Note: The samples are still not building cleanly, there's more errors behind this one.

Checklist

Note that /azp run currently isn't working for this repo.

• Samples build and run using the Visual Studio versions listed in the Windows development docs.
• Samples build and run on all supported platforms (x64, x86, ARM64) and configurations (Debug, Release).
• Samples set the minimum supported OS version to Windows 10 version 1809.
• Samples build clean with no warnings or errors.
• [For new samples]: Samples have completed the sample guidelines checklist and follow standardization/naming guidelines.
• Microsoft employees only: you can validate your changes by following the instructions here: https://www.osgwiki.com/wiki/WindowsAppSDK-Samples

[adrastogi]

Thanks, Mark Schofield (@mschofie)! This looks good to me, but I've also tagged some folks from the WASDK team to take a look in case there are implications of this change I might not be aware of.

[Scott Jones (Scottj1s)]

This is fine - we may have to revisit when agg starts building against main branch samples (and no longer references nuget.org directly)

[Mark Schofield (mschofie)]

It looks like this might break BackgroundTask samples, since they depend on version 10.0.26100.2161 of "Microsoft.Windows.SDK.BuildTools" which isn't on nuget.org.

I'm trying to buddy build all samples, but it's a bit tricky :/

[Mark Schofield (mschofie)]

Hmm... So "Microsoft.Windows.SDK.BuildTools" version "10.0.26100.2161" isn't available on either source:

• https://pkgs.dev.azure.com/shine-oss/WinAppSDK-Samples/_packaging/WinAppSDK-SampleDeps/nuget/v3/index.json
• https://api.nuget.org/v3/index.json

So the problems I'm seeing with that are unrelated to my changes.

[Scott Jones (Scottj1s)]

Hmm... So "Microsoft.Windows.SDK.BuildTools" version "10.0.26100.2161" isn't available on either source:
So the problems I'm seeing with that are unrelated to my changes.

Thanks Mark - totally up to you if you want to update those references to latest, 10.0.26100.6584

[Mark Schofield (mschofie)]

Thanks, Scott, I've filed #558 to track the work. I think that completes due diligence for this PR.