In EAP7.2.x there has been also implemented change to preserve original behavior with possibility to change the behavior via a system property 'io.undertow.servlet.dispatch.preserve_path_of_forward', see
JBEAP-16448 and JBEAP-16644. Although, no such change has been introduced into upstream WildFly. So I assume that in EAP7.3.0, the default behavior will now copy the default in Undertow and also there will be no possibility to change the new behavior back in any way (please correct me if I am wrong).
Since specification on this may be explained different ways (e.g. comment here and discussion here), customer may incline to one or another implementations. Thus, I am raising this issue to introduce possibility to configure this change of behavior also from EAP 7.3.0 side - will require addition into WildFly upstream though.
Note: There has been already created a doc issue into migration guide that should address change in default behavior
JBEAP-16449 in EAP7.3.0.