I’m new in Xwiki and and installed the application in a server with Tomcat and Apache. I downloaded the 10.4 version WAR.
I created two vhosts on my Apache (with a proxy, because Tomcat), one to http and other to https.
In http the page load correctly, but in https it load a kind of broken.
Setting this property is not required at all, by default the protocol will be taken from the input request and if the proxy is properly configured XWiki will see it’s an https request. Also this is only for external URLs which is not really something XWiki produce much unless you manipulate cross wikis resources (or for mails).