Don't require AttributeProvider for JsonPropertyInfo-based modifications

src/OpenApi/src/Services/Schemas/OpenApiSchemaService.cs

@@ -91,7 +91,7 @@ internal sealed class OpenApiSchemaService(
             schema.ApplyPrimitiveTypesAndFormats(context);
             schema.ApplySchemaReferenceId(context);
             schema.ApplyPolymorphismOptions(context);
-            if (context.PropertyInfo is { AttributeProvider: { } attributeProvider } jsonPropertyInfo)
+            if (context.PropertyInfo is { } jsonPropertyInfo)
             {
                 // Short-circuit STJ's handling of nested properties, which uses a reference to the
                 // properties type schema with a schema that uses a document level reference.
@@ -102,6 +102,9 @@ internal sealed class OpenApiSchemaService(
                     return new JsonObject { [OpenApiSchemaKeywords.RefKeyword] = context.TypeInfo.GetSchemaReferenceId() };
                 }
                 schema.ApplyNullabilityContextInfo(jsonPropertyInfo);
+            }
+            if (context.PropertyInfo is { AttributeProvider: { } attributeProvider })
+            {
                 if (attributeProvider.GetCustomAttributes(inherit: false).OfType<ValidationAttribute>() is { } validationAttributes)
                 {
                     schema.ApplyValidationAttributes(validationAttributes);

src/OpenApi/test/Services/OpenApiDocumentServiceTestsBase.cs

@@ -98,8 +98,9 @@ internal static OpenApiDocumentService CreateDocumentService(IEndpointRouteBuild
         provider.OnProvidersExecuted(context);
 
         var apiDescriptionGroupCollectionProvider = CreateApiDescriptionGroupCollectionProvider(context.Results);
+        var jsonOptions = builder.ServiceProvider.GetService<IOptions<Microsoft.AspNetCore.Http.Json.JsonOptions>>() ?? Options.Create(new Microsoft.AspNetCore.Http.Json.JsonOptions());
 
-        var schemaService = new OpenApiSchemaService("Test", Options.Create(new Microsoft.AspNetCore.Http.Json.JsonOptions()), builder.ServiceProvider, options.Object);
+        var schemaService = new OpenApiSchemaService("Test", jsonOptions, builder.ServiceProvider, options.Object);
         ((TestServiceProvider)builder.ServiceProvider).TestSchemaService = schemaService;
         var documentService = new OpenApiDocumentService("Test", apiDescriptionGroupCollectionProvider, hostEnvironment, options.Object, builder.ServiceProvider);
         ((TestServiceProvider)builder.ServiceProvider).TestDocumentService = documentService;

src/OpenApi/test/Services/OpenApiSchemaService/OpenApiSchemaService.RequestBodySchemas.cs

@@ -4,8 +4,10 @@
 using System.ComponentModel;
 using System.ComponentModel.DataAnnotations;
 using System.IO.Pipelines;
+using System.Text.Json.Serialization.Metadata;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.OpenApi.Any;
 using Microsoft.OpenApi.Models;
 
@@ -468,6 +470,51 @@ await VerifyOpenApiDocument(builder, document =>
         });
     }
 
+    [Fact]
+    public async Task SupportsNestedTypes_WithNoAttributeProvider()
+    {
+        // Arrange: this test ensures that we can correctly handle the scenario
+        // where the attribute provider is null and we need to patch the property mappings
+        // that are created by the underlying JsonSchemaExporter.
+        var serviceCollection = new ServiceCollection();
+        serviceCollection.ConfigureHttpJsonOptions(options =>
+        {
+            options.SerializerOptions.TypeInfoResolver = options.SerializerOptions.TypeInfoResolver?.WithAddedModifier(jsonTypeInfo =>
+            {
+                foreach (var propertyInfo in jsonTypeInfo.Properties)
+                {
+                    propertyInfo.AttributeProvider = null;
+                }
+
+            });
+        });
+        var builder = CreateBuilder(serviceCollection);
+
+        // Act
+        builder.MapPost("/api", (NestedType type) => { });
+
+        // Assert
+        await VerifyOpenApiDocument(builder, document =>
+        {
+            var operation = document.Paths["/api"].Operations[OperationType.Post];
+            var requestBody = operation.RequestBody;
+            var content = Assert.Single(requestBody.Content);
+            Assert.Equal("NestedType", content.Value.Schema.Reference.Id);
+            var schema = content.Value.Schema.GetEffective(document);
+            Assert.Collection(schema.Properties,
+                property =>
+                {
+                    Assert.Equal("name", property.Key);
+                    Assert.Equal("string", property.Value.Type);
+                },
+                property =>
+                {
+                    Assert.Equal("nested", property.Key);
+                    Assert.Equal("NestedType", property.Value.Reference.Id);
+                });
+        });
+    }
+
     private class DescriptionTodo
     {
         [Description("The unique identifier for a todo item.")]