In the [Getting Started](https://github.com/elastic/elasticsearch-net-abstractions/blob/master/src/Elastic.Xunit/README.md#getting-started) example there's this package reference: ``` <PackageReference Include="Elastic.Xunit" Version="<latest>" /> ``` Is `Elastic.Xunit` meant to be a NuGet package (which I [cannot find](https://www.nuget.org/packages?q=Elastic.Xunit)) or should it be included from source?