public async Task <ActionResult> Get(string uri)
        {
            using var httpClient = new HttpClient();

            var str = await httpClient.GetStringAsync(uri);

            // Read V3 as YAML
            var openApiDocument = new OpenApiStringReader().Read(str, out var diagnostic); // new OpenApiStreamReader().Read(stream, out var diagnostic);

            // Write V2 as JSON
            var outputString = openApiDocument.Serialize(OpenApiSpecVersion.OpenApi2_0, OpenApiFormat.Json);

            return(Ok(openApiDocument));
        }