public final class HandlerHelper
Manages all of the logic ADFMetadataUpgradeHandler retrieval, invocation, and error handling.
A handlerNamespace to handlerClassName Map is loaded as a private variable on new instance creation. This map is
initialized with the contents of META-INF/services/adf-metadata-upgrade.properties. HandlerHelper will try to load all
.properties file matches, maintaining the previous handlerNamespace -> handlerClassName mapping in case of duplicates.
Note: if all the .properties files are empty, the assumption is that the application will not participate in Upgrade (no failure).