code: public void addPlugin(ComponentPlugin plugin)
     {
        if (RegistryInitializationEntryPlugin.class.isAssignableFrom(plugin.getClass()))
        {
           RegistryInitializationEntryPlugin registryPlugin = (RegistryInitializationEntryPlugin)plugin;
           appConfigurations = registryPlugin.getAppConfiguration();
           entryLocation = registryPlugin.getLocation();
           if (entryLocation == null)
              entryLocation = EXO_APPLICATIONS;
        }
     }
docs: Defines the configuration of the service thanks to the provided plugin if and
  only if the plugin is of type {@link RegistryInitializationEntryPlugin}
  @param plugin the plugin from which we extract the configuration that is expected
  to be of type {@link RegistryInitializationEntryPlugin}