Major Description
The current PluginManager implementation knows a hardcode list of classes to export as OSGi system packages. This approach makes it difficult for broker plugins authors as they have no means to extend the list.
This improvement will extract the list to a separate properties file with the ability to override the properties file in use via System Propery (utilizing the existing FileUtils#openFileOrDefaultResource method).
It will also remove the need for PluginManager to be manually editted with each Qpid release.
https://cwiki.apache.org/confluence/display/qpid/Source+files+containing+version+numbers