Increase SwaggerJsonTransformer.Transform performance with cache

[teomane]

My growing project is experiencing poor performance with the Transform method. Would you consider caching the transformed version to improve performance? Let say:

public string Transform(
            string swaggerJson,
            IEnumerable<RouteOptions> routes,
            string serverOverride,
            SwaggerEndPointOptions endPointOptions)
        {
            return _memoryCache.GetOrCreate(
                ComputeHash(swaggerJson),
                _ =>
                {
                    var swagger = JObject.Parse(swaggerJson);

                    if (swagger.ContainsKey("swagger"))
                    {
                        return TransformSwagger(swagger, routes, serverOverride, endPointOptions);
                    }

                    if (swagger.ContainsKey("openapi"))
                    {
                        return TransformOpenApi(swagger, routes, serverOverride, endPointOptions);
                    }

                    throw new InvalidOperationException("Unknown swagger/openapi version");
                });
        }

[Burgyn]

What you write makes sense. If you have time, you can prepare a pull request. Consider setting the cache expiration (if it is set to 0, it won't cache at all)