Chore/sync main to feat 3 2

.github/workflows/ci-cd.yml

@@ -76,7 +76,7 @@ jobs:
         working-directory: ./performance/benchmark
 
       - name: Publish benchmark results
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           if-no-files-found: error
           name: benchmark-results

.release-please-manifest.json

@@ -1,3 +1,3 @@
 {
-  ".": "2.3.8"
+  ".": "2.3.9"
 }

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## [2.3.9](https://github.com/microsoft/OpenAPI.NET/compare/v2.3.8...v2.3.9) (2025-11-06)
+
+
+### Bug Fixes
+
+* a bug where null sentinel value would appear in YAML documents ([0e864c7](https://github.com/microsoft/OpenAPI.NET/commit/0e864c73791b8610a95f06da9fbb44bfa1cf75a9))
+* a bug where null sentinel value would appear in YAML documents ([15618e1](https://github.com/microsoft/OpenAPI.NET/commit/15618e1f6a79874ae61dc31e3bcd5e1f3177d7ff))
+
 ## [2.3.8](https://github.com/microsoft/OpenAPI.NET/compare/v2.3.7...v2.3.8) (2025-10-27)
 
 

Directory.Build.props

@@ -12,7 +12,7 @@
     <PackageProjectUrl>https://github.com/Microsoft/OpenAPI.NET</PackageProjectUrl>
     <Copyright>© Microsoft Corporation. All rights reserved.</Copyright>
     <PackageTags>OpenAPI .NET</PackageTags>
-    <Version>2.3.8</Version>
+    <Version>2.3.9</Version>
   </PropertyGroup>
   <!-- https://github.com/clairernovotny/DeterministicBuilds#deterministic-builds -->
   <PropertyGroup Condition="'$(TF_BUILD)' == 'true'">

performance/benchmark/PerformanceTests.csproj

@@ -14,8 +14,8 @@
     <NoWarn>CA1822</NoWarn>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="BenchmarkDotNet" Version="0.15.4" />
-    <PackageReference Include="BenchmarkDotNet.Diagnostics.Windows" Version="0.15.4" />
+    <PackageReference Include="BenchmarkDotNet" Version="0.15.6" />
+    <PackageReference Include="BenchmarkDotNet.Diagnostics.Windows" Version="0.15.6" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\Microsoft.OpenApi\Microsoft.OpenApi.csproj" />

src/Microsoft.OpenApi.YamlReader/YamlConverter.cs

@@ -63,6 +63,10 @@ public static YamlNode ToYamlNode(this JsonNode json)
             {
                 JsonObject obj => obj.ToYamlMapping(),
                 JsonArray arr => arr.ToYamlSequence(),
+                JsonValue nullVal when JsonNullSentinel.IsJsonNullSentinel(nullVal) => new YamlScalarNode("null")
+                {
+                    Style = ScalarStyle.Plain
+                },
                 JsonValue val => val.ToYamlScalar(),
                 _ => throw new NotSupportedException("This isn't a supported JsonNode")
             };

test/Microsoft.OpenApi.Readers.Tests/YamlConverterTests.cs

@@ -2,6 +2,7 @@
 using Microsoft.OpenApi.YamlReader;
 using SharpYaml;
 using SharpYaml.Serialization;
+using System;
 using System.IO;
 using System.Text.Json.Nodes;
 using Xunit;
@@ -302,10 +303,18 @@ from openai import OpenAI
         var jsonNode = ConvertYamlStringToJsonNode(yamlInput);
         var convertedBack = jsonNode.ToYamlNode();
         var convertedBackOutput = ConvertYamlNodeToString(convertedBack);
-    
+
         // Then
         Assert.Equal(yamlInput.MakeLineBreaksEnvironmentNeutral(), convertedBackOutput.MakeLineBreaksEnvironmentNeutral());
     }
+    [Fact]
+    public void ItDoesNotSerializeTheSentinelValue()
+    {
+        var yamlValue = JsonNullSentinel.JsonNull.ToYamlNode();
+
+        var scalarNode = Assert.IsType<YamlScalarNode>(yamlValue);
+        Assert.Equal("null", scalarNode.Value, StringComparer.OrdinalIgnoreCase);
+    }
 
     private static JsonNode ConvertYamlStringToJsonNode(string yamlInput)
     {