displayRequestDuration is not working as expected

Q&A (please complete the following information)

• OS: macOS
• Browser: firefox for developers
• Version: 71.0b1 (64-bit)
• Method of installation: npm
• Swagger-UI version: 3.24.0
• Swagger/OpenAPI version: OpenAPI 3.0

Content & configuration

Swagger-UI configuration options:

% cat swagger-config.yaml
---
url: "https://petstore.swagger.io/v2/swagger.json"
dom_id: "#swagger-ui"
validatorUrl: "https://validator.swagger.io/validator"
displayRequestDuration: true
% 

Describe the bug you're encountering

after adding displayRequestDuration to swagger-config.yaml as per the above and did the build using 'npm run build', and deployed new swagger-ui files:

The request duration is not showing when I use the try it out feature

To reproduce...

Steps to reproduce the behavior:

1. Update file swagger-config.yaml to add "displayRequestDuration: true"
2. run "npm run build"
3. copy files under list/ directory to your website location
4. Open your OAS and use try it out feature then check in the response and you would see that there is no "request duration" box.

Expected behavior

I expect that request duration section appears in try it out feature.

Screenshots

Additional context or thoughts

Start by reproducing the issue with swagger-config.yaml using displayRequestDuration: true, then run npm run build and inspect the generated files under the list/ directory. Use the Try It Out flow against the provided Petstore URL and compare the response view with the expected request duration section. Done means the duration is displayed after a request when the option is enabled.