I finally found the correct answer for this CXF-based case.
CXF already has runtime schema validation built-in. It is named schema validation via configuration and the only thing that was missing in my code was the XML to enable it, inside the already existing <jaxws:endpoint
element in beans.xml
AKA application-context.xml
:
<jaxws:properties>
<entry key="schema-validation-enabled" value="true" />
</jaxws:properties>
This discovery was made possible thanks to the answer by @Patrick.