Last-modified response header date-time wrongly formatted in Response headers box

[tomeksamcik]

Q&A

• OS: macOS Monterey 12.4
• Browser: Chrome
• Version: 105.0.5195.102 (arm64)
• Method of installation: docker
• Swagger-UI version: 4.14.0
• OpenAPI version: OpenAPI 3.0.0

Content & configuration

Example Swagger/OpenAPI definition:

(...)
  200:
     description: (...)
     headers:
        Last-Modified:
           description: (...)
           schema:
              type: string
              format: HTTP-date
              example: Fri, 27 Sep 2019 11:00:00 GMT
(...)  

Swagger-UI is in it's default configuration.

Describe the bug you're encountering

When testing an endpoint that is returning http Last-modified header, in the swagger Response headers box, instead of having them displayed raw as they are returned from the server, headers are lowercased (not an issue) and Last-modified is reformatted in a way that it no longer conforms to HTTP-date format (RFC2616)

Sending it in this format in If-Modified-Since header may then result in ignoring it as that's what http protocol tells to do (RFC7232).

To reproduce...

Nothing special:

1. Go to swagger-ui
2. Click on Try it out and Execute request returning Last-modified
3. Scroll down to Response headers
4. See how Last-modified is wrongly formatted

Expected behavior

Instead of Fri,20 Jul 2018 20:23:07 GMT, it should be Fri, 20 Jul 2018 20:23:07 GMT

Screenshots

Server response headers:

Swagger response headers box:

[vidaritos]

This also happens with the Date and Expires response headers (and most likely other date response fields, if any)
{"swaggerUI":{"version":"5.17.10","gitRevision":"gb5c84f44","gitDirty":true,"buildTimestamp":"Wed, 15 May 2024 14:13:17 GMT"}}

I was playing around with conditional requests and wasted a lot of time to figure this bug out because I copied the Last-Modified response header value into the If-Modified-Since input field and the server failed to parse the date and gave me HTTP 200 when I expected HTTP 304

Edit: Think it's this line
https://github.com/swagger-api/swagger-ui/blob/0ce792c9d0965a8b6b5d75f5e1341ff6936a4cb0/src/core/components/live-response.jsx#L66C33-L66C40

It's not really about dates, but rather that the header value contains ", " (comma space)
Ex response:
Server: X-Header: A, B, C, D, , , , test, test
Swagger UI: x-header: A,B,C,D,,,,test, test