[gatsby-plugin-sitemap] - why remove trailing slash?

Summary

The plugin gatsby-plugin-sitemap removes trailing slashes from paths. For example: https://www.example.com/test/ becomes https://www.example.com/test in the generated sitemap.xml

Relevant information

It seems that by design Gatsby redirects to path’s with trailing slashes server-side, for example

$ curl -I http://localhost:9000/test
HTTP/1.1 301 Moved Permanently
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept
Content-Type: text/html; charset=UTF-8
Content-Length: 177
Content-Security-Policy: default-src 'none'
X-Content-Type-Options: nosniff
Location: /test/
Vary: Accept-Encoding
Date: Mon, 14 Oct 2019 14:35:20 GMT
Connection: keep-alive

Where /test has a 301 redirect to /test/.

The result is that Search Engines (e.g. Google) that read the sitemap flag the pages as Duplicate, submitted URL not selected as canonical. If Gatsby (express) intends paths to end in a trailing slash, then this should be the same in the sitemap.xml. However this function removes the trailing slash in the sitemap.

[mniederm]

Hi I have still the same problem. No trailing slash in the sitemap and no slash at canonical urls.

[rudolphfunk]

Would like to keep this open to understand why there is a difference in the resulting sitemap output,