code: @Override
  	public void shutdown(IAggregator aggregator) {
  		for(IServiceRegistration reg : serviceRegistrations) {
  			reg.unregister();
  		}
  		serviceRegistrations.clear();
  		aggregator = null;
  	}
docs: /* (non-Javadoc)
  @see com.ibm.jaggr.core.IShutdownListener#shutdown(com.ibm.jaggr.core.IAggregator)