With 'proxy-address-forwarding="true"' X-Forwarded-* headers are used by Undertow to show the correct URLs. There was some changes done in https://issues.jboss.org/browse/UNDERTOW-756 which results in ':80' being added to the port when X-Forwarded-Host doesn't include a port. This results in the request URL being 'http://hostname:80' and worse 'https://hostname:80'.

Looking at the comments in https://issues.jboss.org/browse/UNDERTOW-756 there was a fix for this added in https://github.com/undertow-io/undertow/pull/430, but it looks like this commit didn't make it into EAP 7.0.3.