Question about spinner.gif in css

Hello.

I have xwiki 10.9 based on docker-image from https://hub.docker.com/_/xwiki/

It works with nginx (reverse-proxy) on url https://wiki.xxx.ru in our organization network.

There is an error in browser console:

jquery.js:5799 GET https://cedar.xxx.ru/resources/icons/xwiki/spinner.gif 404 (Not Found)

 

We have this address in our organization (cedar.xxx.ru), but how can it be in xwiki css file?

.jstree-xwiki>.jstree-container-ul .jstree-loading>.jstree-ocl

{ background-image: url("https://cedar.xxx.ru:443/resources/icons/xwiki/spinner.gif"); background-position: center center!important; background-size: 16px }

with evaluate=true:

https://wiki.xxx.ru/webjars/wiki%3Axwiki/xwiki-platform-tree-webjar/10.9/tree.min.css?evaluate=true
.jstree-container-ul .jstree-loading>.jstree-ocl{background-image:url("https://cedar.xxx.ru:443/resources/icons/xwiki/spinner.gif");

without evaluate=true:

https://wiki.xxx.ru/webjars/wiki%3Axwiki/xwiki-platform-tree-webjar/10.9/tree.min.css
.jstree-container-ul .jstree-loading>.jstree-ocl{background-image:url("$!xwiki.getSkinFile('icons/xwiki/spinner.gif')");

If I set xwiki.home variable (in xwiki.cfg) to correct url (https://wiki.xxx.ru) - those spinner errors in console are not present. And tree.min.css contains another path to spinner.gif:

https://wiki.xxx.ru/webjars/wiki%3Axwiki/xwiki-platform-tree-webjar/10.9/tree.min.css?evaluate=true
.jstree-container-ul .jstree-loading>.jstree-ocl{background-image:url("https://wiki.xxx.ru/resources/icons/xwiki/spinner.gif")

But with set xwiki.home value we get errors with rest (i.e. deletion

• GET https://rest/jobstatus/refactoring/delete/1539654907694-325?media=json 0 () ...

Deletion process freezes on "Please wait while the page is being deleted.". This error is displayed in web console, but the page is deleted.
)

 

How can I feagure out where that "cedar.xxx.ru" comes from ?