'licenseUrl' as package metadata is now deprecated, use 'license' instead

[anangaur]

As announced earlier about our aim to remove content Urls (license, icons and markdown documentation) from the package and make these metadata part of the package, we have now deprecated the use of licenseUrl as package metadata. You can now use license field in the nuspec, instead.

For reference, here are the planned milestones for this feature:
Milestone 1 (Today):

• NuGet.exe v4.9.2 and dotnet.exe (that ships with .NET SDK – 2.1.502 and 2.2.101) supports creating packages using the new “license” property
• Providing “LicenseURL” during pack time is deprecated and a warning is shown if used.
• NuGet.org accepts packages that contain the “license” property, including license files.
• License information (expression or file) is exposed through Package Manager UI in Visual Studio.
• Visual Studio 2017 15.9.4 and above supports surfacing the new “license” property.

Milestone 2:

• We will monitor the adoption of clients that can understand the “license” property and NuGet.org will disable the use of licenseUrl when that adoption has reached a threshold.

Links:

• Feature announcement: Packaging Icon, License and Documentation within the nupkg
• Spec wiki: Packaging License within the nupkg
• Discussion issue: Self-Contained NuGet Packages – License #4628
• Documentation for license metadata in nuspec: https://docs.microsoft.com/en-us/nuget/reference/nuspec#license
• Documentation for license metadata using MSBuild properties in project file: https://docs.microsoft.com/en-us/nuget/reference/msbuild-targets#packing-a-license-expression-or-a-license-file