Pages with includes are cached without (default) included referenced content

I am having a similar issue, though with different steps to reproduce.

Steps to reproduce

1. Create an endpoint with a default include
2. Make sure Drupal cache is enabled
3. Clear the cache (and ensure max-age on cache on below requests has also expired)
4. Request the created endpoint without any includes eg /jsonapi/node/page?include=
5. Request the created endpoint as default eg /jsonapi/node/page and see that it is serving the response without includes from previous step

This issue seems to have been introduced with 🐛 Pages with default includes are not cached Fixed in v3.25. If I roll back to 3.24 the issue is not present.

Ok, so what i understand.

/jsonapi/node/page?include=: A page with includes cleared.

is cached the same as

/jsonapi/node/page: A page with default includes.

That indeed seems like a regression. We should able to test that pretty easily in this test somewhere:

JsonApiDefaultsFunctionalTest

Tried to reproduce in tests, couldn't reproduce the first case (IS) but seems i can reproduce the second case by @cb_dewr.

I think this is fixed now. Problem was indeed the difference of `include=` versus no include paramter at all. I would love a review on this, perhaps test this patch on your site.