From https://github.com/jboss-developer/jboss-eap-quickstarts/issues/1722 by rafael.soares

"Some webapp projects are referencing broken Bootstrap CSS links.

For example you can observe this on payment-cdi-event JSF Facelets template file

This older version (1.4.0) of bootstrap library can be found at: https://bootstrapdocs.com/v1.4.0/bootstrap.min.css

Would be nice to upgrade the bootstrap version used by JBoss quickstarts or use some kind of JS/CSS package manager tool (eg: Bower). This would be a good idea specially for modern web apps that use many JS/CSS frameworks...."