Resolved: How can I generate at compile-time a separate OpenAPI Swagger.json file for each Controller in my ASP.NET project?

public static class WebApplicationExtensions
{
    public static async Task GenerateSwaggerFilesAsync(this WebApplication app, string folderPath)
    {
        Console.WriteLine($"Generating Swagger Files > \"{Path.GetFullPath(folderPath)}\"");

        if (Directory.Exists(folderPath))
        {
            Directory.Delete(folderPath, true);
        }

        var apiGroups = app.Services.GetService<IApiDescriptionGroupCollectionProvider>()!.ApiDescriptionGroups;
        foreach (var apiGroup in apiGroups.Items)
        {
            var settings = new AspNetCoreOpenApiDocumentGeneratorSettings
            {
                Title = apiGroup.GroupName,
                DocumentName = apiGroup.GroupName,
                ApiGroupNames = new string[] { apiGroup.GroupName! },
                SchemaType = NJsonSchema.SchemaType.OpenApi3,
                SerializerSettings = new JsonSerializerSettings
                {
                    ContractResolver = new CamelCasePropertyNamesContractResolver()
                }
            };

            // TODO: Add any processors you want
            settings.OperationProcessors.Add(new ActionNameOperationProcessor());

            var apiGenerator = new AspNetCoreOpenApiDocumentGenerator(settings);

            var apiDocument = await apiGenerator.GenerateAsync(apiGroups);

            var json = apiDocument.ToJson();

            var subFolder = folderPath.UrlCombine(apiGroup.GroupName!);

            Directory.CreateDirectory(subFolder);

            var file = $"{subFolder}/swagger.json";

            await File.WriteAllTextAsync(file, json);
        }

        if (app.Configuration["generate-swagger"] == "true")
        {
            await app.StopAsync();
            Environment.Exit(0);
        }
    }

    public class ActionNameOperationProcessor : IOperationProcessor
    {
        public bool Process(OperationProcessorContext context)
        {
            var aspNetCoreContext = (AspNetCoreOperationProcessorContext)context;
            var controllerActionDescriptor = (ControllerActionDescriptor)aspNetCoreContext.ApiDescription.ActionDescriptor;

            context.OperationDescription.Operation.OperationId = controllerActionDescriptor.ActionName;
            context.OperationDescription.Operation.Tags = new List<string> { aspNetCoreContext.ApiDescription.GroupName! };

            return true;
        }
    }

}

app.MapControllers();

// Generate Swagger
await app.GenerateSwaggerFilesAsync("./.swagger");

app.Run();

<Target Name="GenerateSwagger" AfterTargets="Build" Condition="'$(Configuration)'=='Debug'">
    <Exec WorkingDirectory="$(RunWorkingDirectory)" Command="$(RunCommand) --generate-swagger true" />
</Target>