The org.wildfly.extension.undertow module declares its dep on org.wildfly.common as optional. That may have been correct when the module dep was added but it isn't correct today – UndertowRootDefinition, ExchangeAttributeDefinitions and UndertowDeploymentProcessor all require classes from WildFly Common.

I'll mark this as Minor because I expect in all slimmed server provisioning scenarios org.wildfly.common ends up being provisioned anyway.