SourceRoot error with SourceLinkVstsGitDomain

I'm getting build warnings when building my project in VSTS against Git. The warning is:

C:\Users\VssAdministrator\.nuget\packages\microsoft.sourcelink.common\1.0.0-beta-62925-02\build\Microsoft.SourceLink.Common.targets (60, 5)
C:\Users\VssAdministrator\.nuget\packages\microsoft.sourcelink.common\1.0.0-beta-62925-02\build\Microsoft.SourceLink.Common.targets(60,5): Warning : No SourceRoot items specified - the generated source link is empty.

I added the Microsoft.SourceLink.Vsts.Git package to my project and set the SourceLinkVstsGitDomain to my company's root VSTS URL.

Source linking appears to be working correctly. I blew away my local project source, added the NuGet package to a test solution and I got prompted for the download of the source and could then step through the code. Beyond the warning everything seems to be working correctly. How do I get rid of this warning? Can the docs be updated to reflect the steps involved because right now I cannot find any that specify how to do it correctly. I figured it out from trial and error. Most are referencing the legacy SourceLink packages and/or settings up symbol server stuff.