public void loadGroupDeferred(CogaenId groupId) {
		List<ResourceHandle> group = this.groups.get(groupId);
		if (group == null) {
			throw new RuntimeException("unonkown resource group " + groupId);
		}
		
		this.logger.logInfo(LOGGING_SOURCE, "preloading resource group " + groupId);
		this.deferredIterator = group.iterator();
		this.deferredCounter = 0;
		this.deferredSize = group.size();
	}