Add hook for excluding certain build output extensions from the nuget package

[Anipik]

Currently there is no way to exclude certain output extensions from the package.

https://github.com/NuGet/NuGet.Client/blob/dev/src/NuGet.Core/NuGet.Build.Tasks.Pack/NuGet.Build.Tasks.Pack.targets#L48

adding something like should do the trick

<AllowedOutputExtensionsInPackageBuildOutputFolder Condition="'$(AllowedOutputExtensionsInPackageBuildOutputFolder)' == ''">.dll; .exe; .winmd; .json; .pri; .xml; $(AllowedOutputExtensionsInPackageBuildOutputFolder)</AllowedOutputExtensionsInPackageBuildOutputFolder>

cc @safern @nkolev92 @ericstj @ViktorHofer

[ViktorHofer]

Currently there is no way to exclude certain output extensions from the package.

Can't you override that property in a target before the PackTask is executed?

adding something like should do the trick

Makes sense to me. I don't think this change requires much discussion. cc @nkolev92

[ericstj]

What happens to an existing project that set AllowedOutputExtensionsInPackageBuildOutputFolder=.foo?

[ViktorHofer]

Oh I did misread the proposal above.

I see 31 hits of that property being used in the dotnet org alone: https://github.com/search?q=org%3Adotnet+AllowedOutputExtensionsInPackageBuildOutputFolder&type=code.

And about 3k on GitHub overall: https://github.com/search?q=AllowedOutputExtensionsInPackageBuildOutputFolder&type=code.

[nkolev92]

I don't have many concerns. If you add a default value that is set conditionally, you could avoid breaking people that are using this to include extra files.

    <DefaultAllowedOutputExtensionsInPackageBuildOutputFolderCondition="'$(DefaultAllowedOutputExtensionsInPackageBuildOutputFolderCondition)' == ''">dll; .exe; .winmd; .json; .pri; .xml</DefaultAllowedOutputExtensionsInPackageBuildOutputFolderCondition>
    <AllowedOutputExtensionsInPackageBuildOutputFolder>$(DefaultAllowedOutputExtensionsInPackageBuildOutputFolderCondition); $(AllowedOutputExtensionsInPackageBuildOutputFolder)</AllowedOutputExtensionsInPackageBuildOutputFolder>

Maybe something less wordy :D

[Anipik]

Thanks @nkolev92, i will put up a pr for it.