Disable nullability warnings in JSON source generator

src/libraries/System.Text.Json/gen/JsonSourceGenerator.Emitter.cs

@@ -152,7 +152,8 @@ private void AddSource(string fileName, string source, bool isRootContextDef = f
                 bool isInGlobalNamespace = @namespace == JsonConstants.GlobalNamespaceValue;
 
                 StringBuilder sb = new(@"// <auto-generated/>
-#nullable enable
+#nullable enable annotations
+#nullable disable warnings
 
 // Suppress warnings about [Obsolete] member usage in generated code.
 #pragma warning disable CS0618");

src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Tests/JsonSerializerContextTests.cs

@@ -380,6 +380,21 @@ public static void SupportsGenericParameterWithCustomConverterFactory()
             Assert.Equal(@"[""Cee""]", json);
         }
 
+        // Regression test for https://github.com/dotnet/runtime/issues/74652
+        [Fact]
+        public static void ClassWithStringValuesRoundtrips()
+        {
+            JsonSerializerOptions options = ClassWithStringValuesContext.Default.Options;
+
+            ClassWithStringValues obj = new()
+            {
+                StringValuesProperty = new(new[] { "abc", "def" })
+            };
+
+            string json = JsonSerializer.Serialize(obj, options);
+            Assert.Equal("""{"StringValuesProperty":["abc","def"]}""", json);
+        }
+
         [JsonConverter(typeof(JsonStringEnumConverter))]
         public enum TestEnum
         {
@@ -394,7 +409,11 @@ internal partial class GenericParameterWithCustomConverterFactoryContext : JsonS
         [JsonSerializable(typeof(ClassWithPocoListDictionaryAndNullable))]
         internal partial class ClassWithPocoListDictionaryAndNullablePropertyContext : JsonSerializerContext
         {
+        }
 
+        [JsonSerializable(typeof(ClassWithStringValues))]
+        internal partial class ClassWithStringValuesContext : JsonSerializerContext
+        {
         }
 
         internal class ClassWithPocoListDictionaryAndNullable

src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Tests/System.Text.Json.SourceGeneration.Tests.targets

@@ -112,6 +112,10 @@
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\DynamicallyAccessedMemberTypes.cs" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Extensions.Primitives\src\Microsoft.Extensions.Primitives.csproj" />
+  </ItemGroup>
+
   <Target Name="FixIncrementalCoreCompileWithAnalyzers" BeforeTargets="CoreCompile">
     <ItemGroup>
       <CustomAdditionalCompileInputs Include="@(Analyzer)" />

src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Tests/TestClasses.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
+using Microsoft.Extensions.Primitives;
 
 namespace System.Text.Json.SourceGeneration.Tests.RepeatedTypes
 {
@@ -275,4 +276,9 @@ public class PublicTestClass
     {
         internal class InternalNestedClass { }
     }
+
+    public sealed class ClassWithStringValues
+    {
+        public StringValues StringValuesProperty { get; set; }
+    }
 }