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));
}