I was trying to follow this post for setting the owner of a SharePoint group using client side code. Evidently the REST
/_api/web/sitegroups(id)/owners endpoint isn't functional.
The XML formatting requires the SPSite and the SPWeb id/guid. I was able to get the SPWeb id using the
/_api/web/id REST endpoint -- easy-peasy!
I am a site collection admin, but don't have access to Central admin. Using the same web/id endpoint on the site at the site collection would return the web id, but that is different than the site id.
I was poking everywhere in the site settings hoping to find the siteid as a parameter in a url or something, but was unsuccessful until I did Search Configuration Export. I was able to find the SPSiteId in the exported XML.