There is a system dependency path "sun/security/provider/certpath" missing from modules\system\layers\base\sun\jdk\main\module.xml. This is causing class def not found exception when attempting to create an instance of a class from that namespace. The module contents (abbreviated) are shown below. Notice that the path to "sun/security/provider/certpath" is not listed in there:

{{<module xmlns="urn:jboss:module:1.3" name="sun.jdk">
<resources>
<!-- currently jboss modules has not way of importing services from
classes.jar so we duplicate them here -->
<resource-root path="service-loader-resources"/>
</resources>
<dependencies>
<module name="sun.scripting" export="true"/>
<system export="true">
<paths>
...
<path name="sun/security/action"/>
<path name="sun/security/pkcs"/>
<path name="sun/security/x509"/>
<path name="sun/security"/>
<path name="sun/security/util"/>
<path name="sun/security/krb5"/>
<path name="sun/security/krb5/internal"/>
<path name="sun/security/pkcs11"/>
<path name="sun/security/provider"/>
...
</paths>
<exports>
<include-set>
<path name="META-INF/services"/>
</include-set>
</exports>
</system>
</dependencies>
</module>

}}Manually adding the missing system dependency path fixes the issue.