Consider returning reference type from `AddComponent` API

まず、AddComponent API の実装と、ドキュメントコンポーネントの登録に関する既存のカバレッジを確認します。現在の boolean 結果を AddOperationTransformer の例と比較し、返された参照が挿入されたスキーマを表していることを確認するとともに、既存の登録動作が維持されていることを確認します。

The AddComponent API currently returns a boolean that indicates if the addition of the component to the document registry succeeded.

It would be nice if the API returned a reference to the item that was just constructed. In an M.A.OpenAPI transformer, I currently need to write:

options.AddOperationTransformer((operation, context, cancellationToken) =>
{
    var schemaService = context.ApplicationServices.GetRequiredKeyedService<IOpenApiSchemaService>(context.DocumentName);
    if (context.Description.RelativePath == "error")
    {
        var errorSchema = schemaService.GetOrCreateSchema(typeof(ProblemDetails));
        context.Document.AddComponent("Error", errorSchema);
        operation.Responses["500"] = new OpenApiResponse
        {
            Description = "Error",
            Content =
            {
                ["application/problem+json"] = new OpenApiMediaType
                {
                    Schema = new OpenApiSchemaReference("Error", context.Document),
                },
            },
        };
    }
    return Task.CompletedTask;
});

but would like to write:

options.AddOperationTransformer((operation, context, cancellationToken) =>
{
    var schemaService = context.ApplicationServices.GetRequiredKeyedService<IOpenApiSchemaService>(context.DocumentName);
    if (context.Description.RelativePath == "error")
    {
        var errorSchema = schemaService.GetOrCreateSchema(typeof(ProblemDetails));
        var insertedSchema = context.Document.AddComponent("Error", errorSchema);
        operation.Responses["500"] = new OpenApiResponse
        {
            Description = "Error",
            Content =
            {
                ["application/problem+json"] = new OpenApiMediaType
                {
                    Schema = insertedSchema,
                },
            },
        };
    }
    return Task.CompletedTask;
});

cc: @baywet I couldn't see if an API that did this existed already and figured I'd add the proposal.