protected void addObject(long id, R item) {
		Long idVal = Long.valueOf(id);
		if(this.records.containsKey(idVal)) {
			throw new IllegalArgumentException("The object with the same ID #"+idVal+" is added twice. Check your memento/record implementation whether you have copied the ID.");
		}
		this.records.put(idVal, Preconditions.checkNotNull(item));
	}