Prob validation prep (#33329)

* Prob validation prep

* Prob validation prep

* Prob validation prep

* Prob validation prep

Author: Rick-Anderson

aspnetcore/fundamentals/openapi/samples/9.x/ProducesProblem/ProducesProblem.csproj

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+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net9.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

aspnetcore/fundamentals/openapi/samples/9.x/ProducesProblem/Program.cs

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+#define SECOND // FIRST SECOND
+#if NEVER
+#elif FIRST
+// <snippet_1>
+using Microsoft.AspNetCore.Http;
+
+var app = WebApplication.Create();
+
+var todos = app.MapGroup("/todos")
+    .ProducesProblem();
+
+todos.MapGet("/", () => new Todo(1, "Create sample app", false));
+todos.MapPost("/", (Todo todo) => Results.Ok(todo));
+
+app.Run();
+
+record Todo(int Id, string Title, bool IsCompleted);
+// </snippet_1>
+#elif SECOND
+// <snippet_2>
+using Microsoft.AspNetCore.Http;
+
+var app = WebApplication.Create();
+
+app.MapGet("/", () =>
+{
+	var extensions = new List<KeyValuePair<string, object>> { new("test", "value") };
+	return TypedResults.Problem("This is an error with extensions",
+                                                       extensions: extensions);
+});
+// </snippet_2>
+#endif

aspnetcore/release-notes/aspnetcore-9/includes/prob_validation.md

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+## Support calling `ProducesProblem` and `ProducesValidationProblem` on route groups
+
+The `ProducesProblem` and `ProducesValidationProblem` extension methods have been updated to support application on route groups, as in the sample below. These methods can be used to indicate that all endpoints in a route group can return `ProblemDetails` or `ValidationProblemDetails` responses for the purposes of OpenAPI metadata.
+
+:::code language="csharp" source="~/fundamentals/openapi/samples/9.x/ProducesProblem/Program.cs" id="snippet_1" :::
+
+## `Problem` and `ValidationProblem` result types support construction with `IEnumerable<KeyValuePair<string, object?>>` values
+
+Prior to this preview, constructing `Problem` and `ValidationProblem` result types in minimal APIs required that the `errors` and `extensions` properties be initialized with an implementation of `IDictionary<string, object?>`. Starting in this release, these construction APIs support overloads that consume `IEnumerable<KeyValuePair<string, object?>>`.
+
+:::code language="csharp" source="~/fundamentals/openapi/samples/9.x/ProducesProblem/Program.cs" id="snippet_2" :::
+
+Thanks to GitHub user "joegoldman2" for this contribution!