@Override
	public Codec<ISeq<Item>, BitGene> codec() {
		return _codec;
	}
Create a new {@code Knapsack} definition with the given

@param items the basic {@link Set} of knapsack items.
@param knapsackSize the maximal knapsack size
@throws NullPointerException if the {@code items} set is {@code null}
jenetics.example/src/main/java/io/jenetics/example/Knapsack.java