The ear-exclusions-cascaded-to-subdeployments setting in jboss-deployment-structure.xml does not work as documented in the xsd:

Flag indicating whether .ear module exclusions should be cascaded to sub-deployments.
When this flag is set to true, module exclusions declared at the .ear level will be
applied (casacaded) to each subdployment defined within the .ear.  This is useful in
cases where an .ear has many subdeployments and it is desired to exclude a module
dependency from every subdeployment within the .ear.

This feature was implemented in https://issues.redhat.com/browse/WFCORE-648

Main PR: https://github.com/wildfly/wildfly-core/pull/834
It is incorrectly looping only over subdeployments explicitly listed in jboss-deployment-structure.xml instead of all subdeployments.

Test case PR: https://github.com/wildfly/wildfly/pull/7672
It is ONLY testing the case where sub-deployment is explicitly listed in jboss-deployment-structure.xml

If a subdeployment is not listed in jboss-deployment-structure.xml the exclusions are not cascasded. Not needing to list each individual sub-deployment was the primary reason for the feature.