Note that this doesn't demonstrate how to integrate with the PicketFence IDM architecture used by eXo
This page is a little difficult to make exact sense of, in terms of this serving as any kind of a reference guide.
Configurations for the RootContainer are loaded first, and then for the PortalContainers.
Services default RootContainer configurations from JAR files: /conf/configuration.xml.
External RootContainer configuration will be found at $exo.conf.dir/configuration.xml.
Services default PortalContainer configurations from JAR files: /conf/$PORTAL/configuration.xml.
Web applications configurations from WAR files /WEB-INF/conf/configuration.xml.
Describes the "external-component-plugins" configuration entity
"See the exhaustive reference in the Kernel reference guide."
resembles Spring IoC