Added alternative license expression URLs to be allowed in without warning into Gallery

src/NuGetGallery/Helpers/LicenseExpressionRedirectUrlHelper.cs

@@ -7,7 +7,7 @@ namespace NuGetGallery.Helpers
 {
     public static class LicenseExpressionRedirectUrlHelper
     {
-        private const string LicenseExpressionDeprecationUrlFormat = "https://licenses.nuget.org/{0}";
+        public const string LicenseExpressionDeprecationUrlFormat = "https://licenses.nuget.org/{0}";
 
         public static string GetLicenseExpressionRedirectUrl(string licenseExpression)
         {

src/NuGetGallery/Services/PackageUploadService.cs

@@ -7,6 +7,7 @@
 using System.Data.SqlClient;
 using System.IO;
 using System.Linq;
+using System.Net;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Xml.Linq;
@@ -170,6 +171,7 @@ private async Task<PackageValidationResult> CheckLicenseMetadataAsync(PackageArc
             var licenseUrl = nuspecReader.GetLicenseUrl();
             var licenseMetadata = nuspecReader.GetLicenseMetadata();
             var licenseDeprecationUrl = GetExpectedLicenseUrl(licenseMetadata);
+            var alternativeDeprecationUrl = GetExpectedAlternativeUrl(licenseMetadata);
 
             if (licenseMetadata == null)
             {
@@ -217,7 +219,7 @@ private async Task<PackageValidationResult> CheckLicenseMetadataAsync(PackageArc
                         string.Join(" ", licenseMetadata.WarningsAndErrors)));
             }
 
-            if (licenseDeprecationUrl != licenseUrl)
+            if (licenseDeprecationUrl != licenseUrl && (alternativeDeprecationUrl == null || alternativeDeprecationUrl != licenseUrl))
             {
                 if (licenseMetadata.Type == LicenseType.File)
                 {
@@ -378,6 +380,25 @@ private static string GetExpectedLicenseUrl(LicenseMetadata licenseMetadata)
             throw new InvalidOperationException($"Unsupported license metadata type: {licenseMetadata.Type}");
         }
 
+        /// <summary>
+        /// 15.9 client does url encoding with <see cref="WebUtility.UrlEncode(string)"/> which
+        /// replaces spaces with "+". We shouldn't work about it, but we should fix the client,
+        /// too.
+        /// </summary>
+        private static string GetExpectedAlternativeUrl(LicenseMetadata licenseMetadata)
+        {
+            if (licenseMetadata != null && licenseMetadata.Type == LicenseType.Expression)
+            {
+                return new Uri(
+                    string.Format(
+                        LicenseExpressionRedirectUrlHelper.LicenseExpressionDeprecationUrlFormat,
+                        WebUtility.UrlEncode(licenseMetadata.License)))
+                    .AbsoluteUri;
+            }
+
+            return null;
+        }
+
         private static bool HasChildElements(XElement xElement)
             => xElement.Elements().Any();
 

tests/NuGetGallery.Facts/Services/PackageUploadServiceFacts.cs

@@ -567,6 +567,24 @@ public async Task WarnsWhenInvalidLicenseUrlSpecifiedWithLicenseFile(string lice
                 Assert.Equal("To provide better experience for older clients when a license file is packaged, <licenseUrl> should be set to 'https://aka.ms/deprecateLicenseUrl'.", result.Warnings[0].PlainTextMessage);
             }
 
+            [Fact]
+            public async Task AcceptsAlternativeLicenseUrl()
+            {
+                _nuGetPackage = GeneratePackageWithLicense(
+                    licenseUrl: new Uri("https://licenses.nuget.org/Apache-1.0%2B+OR+MIT"),
+                    licenseExpression: "Apache-1.0+ OR MIT",
+                    licenseFilename: null,
+                    licenseFileContents: null);
+
+                var result = await _target.ValidateBeforeGeneratePackageAsync(
+                    _nuGetPackage.Object,
+                    GetPackageMetadata(_nuGetPackage));
+
+                Assert.Equal(PackageValidationResultType.Accepted, result.Type);
+                Assert.Null(result.Message);
+                Assert.Empty(result.Warnings);
+            }
+
             [Theory]
             [InlineData(null)]
             [InlineData(RegularLicenseUrl)]