PersistentResourceDefinition and PersistentResourceXMLDescription were originally tightly coupled. Ever since PersistentResourceXMLDescription was modified such that it did not rely on a specific ResourceDefinition implementation (WFCORE-1831), this base class add very little value apart from: auto-registering attributes (even though there are no guarantees that these attributes conform to the reload requirements dictated by this class), and encouraging anti-patterns, like using static ResourceDefinition references.  wildfly-subsystem provides a more flexible mechanism for automating registration of the operations, attributes, capabilities, etc. of a resource, and should generally be preferred.