Handle UNLICENSED NuGet license expression

Signed-off-by: Lakshya Jain <lakshyajain1995@gmail.com>

Author: jainlakshya

CycloneDX.Tests/NugetV3ServiceTests.cs

@@ -482,6 +482,38 @@ public async Task GetComponent_SingleLicenseExpression_ReturnsComponent()
             Assert.Equal("Apache-2.0", component.Licenses.First().License.Id);
         }
 
+        [Fact]
+        public async Task GetComponent_UnlicensedLicenseExpression_MapsToLicenseName()
+        {
+            var nuspecFileContents = @"<?xml version=""1.0"" encoding=""utf-8""?>
+                <package xmlns=""http://schemas.microsoft.com/packaging/2013/05/nuspec.xsd"">
+                <metadata>
+                    <id>testpackage</id>
+                    <license type=""expression"">UNLICENSED</license>
+                </metadata>
+                </package>";
+            var mockFileSystem = new MockFileSystem(new Dictionary<string, MockFileData>
+            {
+                { XFS.Path(@"c:\nugetcache\testpackage\1.0.0\testpackage.nuspec"), new MockFileData(nuspecFileContents) },
+            });
+
+            var mockGitHubService = new Mock<IGithubService>();
+
+            var nugetService = new NugetV3Service(null,
+                mockFileSystem,
+                new List<string> { XFS.Path(@"c:\nugetcache") },
+                mockGitHubService.Object,
+                new NullLogger(), false);
+
+            var component = await nugetService.GetComponentAsync("testpackage", "1.0.0", Component.ComponentScope.Required).ConfigureAwait(true);
+
+            Assert.Single(component.Licenses);
+            Assert.Equal("UNLICENSED", component.Licenses.First().License.Name);
+            Assert.True(string.IsNullOrEmpty(component.Licenses.First().License.Id));
+        }
+
+
+
         [Fact]
         public async Task GetComponent_MultiLicenseExpression_ReturnsComponent()
         {

CycloneDX/Services/NugetV3Service.cs

@@ -262,12 +262,25 @@ public async Task<Component> GetComponentAsync(string name, string version, Comp
             {
                 Action<NuGetLicense> licenseProcessor = delegate (NuGetLicense nugetLicense)
                 {
+                    var identifier = nugetLicense?.Identifier?.Trim();
                     var license = new License();
-                    license.Id = nugetLicense.Identifier;
-                    license.Name = license.Id == null ? nugetLicense.Identifier : null;
+
+                    // UNLICENSED is not a valid SPDX license id, so emit as name instead.
+                    // (Avoids generating invalid CycloneDX output like <id>UNLICENSED</id>.)
+                    if (!string.IsNullOrEmpty(identifier) &&
+                        string.Equals(identifier, "UNLICENSED", StringComparison.OrdinalIgnoreCase))
+                    {
+                        license.Name = "UNLICENSED";
+                    }
+                    else
+                    {
+                        license.Id = identifier;
+                    }
+
                     component.Licenses ??= new List<LicenseChoice>();
                     component.Licenses.Add(new LicenseChoice { License = license });
                 };
+
                 licenseMetadata.LicenseExpression.OnEachLeafNode(licenseProcessor, null);
             }
             else if (_githubService == null)