/**
* Combines two combinations into one by merging the the two combinations' {@link
* Combination.Key}s and adding the payloads together.
*
* @param left Left combination.
* @param right Right combination.
*/
public Combination(final Combination<P> left, final Combination<P> right) {
ValidateAs.notNull(left, "left");
ValidateAs.notNull(right, "right");
this.key = new Key(left.getKey(), right.getKey());
this.payload = left.payload.add(right.payload);
if (this.payload == null) {
throw new IllegalStateException(
left.payload.getClass().getName() + ".add(rhs) cannot return null.");
}
}
public Combination(final int index, final P payload) {
this.key = new Key(index);
this.payload = ValidateAs.notNull(payload, "payload");
}