adobe experience manager sitemap core component, github location

Hello,

We may have to change some of the behavior of the sitemap funciton;

Since the acs commons sitemap has been deprecated a little over a year ago and the aem sitemap core component doesn't have much documentation or support :
I am wondering where can I find the java code being activated once the sitemap checkbox is checked on a site's page.

I may want to change some of its behavior, or simply analyse the code to see how it works.

I cannot find it on the github repo : https://github.com/adobe/aem-core-wcm-components