[Windows] Build warnings with older WinAppSDK version

[MartyIX]

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Description of Change

On the main branch, WinAppSDK 1.6 is mentiond in the warnings when dotnet build ./Microsoft.Maui.BuildTasks.slnf is run:

main

Restore complete (9,7s)
X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Essentials\src\Essentials.csproj]
X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Essentials\src\Essentials.csproj]
  Controls.Xaml.Design net472 succeeded (2,9s) → artifacts\bin\Controls.Xaml.Design\Debug\net472\Microsoft.Maui.Controls.Xaml.DesignTools.dll
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Core\src\Core.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Core\src\Core.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Controls\src\Xaml\Controls.Xaml.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Controls\src\Xaml\Controls.Xaml.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Controls\src\Core\Controls.Core.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Controls\src\Core\Controls.Core.csproj]
X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Graphics\src\Graphics.Win2D\Graphics.Win2D.csproj]
X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Graphics\src\Graphics.Win2D\Graphics.Win2D.csproj]
X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Graphics\src\Graphics\Graphics.csproj]
X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.6.241114003\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Graphics\src\Graphics\Graphics.csproj]

PR

With the PR, dotnet build ./Microsoft.Maui.BuildTasks.slnf does not mention WinAppSdk 1.6:

Restore complete (7,8s)
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Core\src\Core.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Core\src\Core.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Essentials\src\Essentials.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Essentials\src\Essentials.csproj]
  Controls.Xaml.Design net472 succeeded (2,8s) → artifacts\bin\Controls.Xaml.Design\Debug\net472\Microsoft.Maui.Controls.Xaml.DesignTools.dll
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Controls\src\Core\Controls.Core.csproj]
  Controls.Core.Design net472 succeeded (3,5s) → artifacts\bin\Controls.Core.Design\Debug\net472\Microsoft.Maui.Controls.DesignTools.dll
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Controls\src\Core\Controls.Core.csproj]
  Graphics netstandard2.1 succeeded (3,3s) → artifacts\bin\Graphics\Debug\netstandard2.1\Microsoft.Maui.Graphics.dll
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Graphics\src\Graphics\Graphics.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Graphics\src\Graphics\Graphics.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Graphics\src\Graphics.Win2D\Graphics.Win2D.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Graphics\src\Graphics.Win2D\Graphics.Win2D.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Controls\src\Xaml\Controls.Xaml.csproj]
X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.BeforeCommon.targets(31,3): warning MSB4011: "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.Build.Msix.props" cannot be imported again. It was already imported at "X:\.nuget\microsoft.windowsappsdk\1.7.250606001\buildTransitive\Microsoft.WinUI.props (22,3)". This is most likely a build authoring error. This subsequent import will be ignored. [X:\maui\src\Controls\src\Xaml\Controls.Xaml.csproj]

Issues Fixed

Fixes #31668

[dotnet-policy-service]

Hey there @@MartyIX! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[jsuarezruiz]

/azp run

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