code: protected void callExtensionInitializers(Iterable<IAggregatorExtension> extensions, ExtensionRegistrar reg) {
  		final String sourceMethod = "callextensionInitializers"; //$NON-NLS-1$
  		boolean isTraceLogging = log.isLoggable(Level.FINER);
  		if (isTraceLogging) {
  			log.entering(AbstractAggregatorImpl.class.getName(), sourceMethod, new Object[]{extensions, reg});
  		}
  		for (IAggregatorExtension extension : extensions) {
  			Object instance = extension.getInstance();
  			if (instance instanceof IExtensionInitializer) {
  				((IExtensionInitializer)instance).initialize(this, extension, reg);
  			}
  		}
  		if (isTraceLogging) {
  			log.exiting(AbstractAggregatorImpl.class.getName(), sourceMethod);
  		}
  	}
docs: For each extension specified, call the extension's
  {@link IExtensionInitializer#initialize} method.  Note that this
  can cause additional extensions to be registered though the
  {@link ExtensionRegistrar}.
  
  @param extensions The list of extensions to initialize
  @param reg The extension registrar.