Unable to Add Refrences Project in Contoso.ModernPosPackagingSample.ModernPos (Sample Project)

[bilalanwer177]

Hi,
I've downloaded the InStore-release-9.41 from GitHub repository, and when I open it in Visual Studio 2017, all the projects are working fine through CSU deployable Package, but when I want to add reference project in Contoso.ModernPosPackagingSample.ModernPos it show warning prompt with this "
Selected Item is not valid reference for this type of project do you want to continue and add al the reference anyway? " and when click on yes it shows some warning icon on refrenced project but not showing any of error, and the customization for ModernPos Installer Isn't working,

Is anybody have a same issue regarding this?