@Override
    public void resolveLevel(int level) {
        if (level == 0) {
            throw new IllegalArgumentException("Operation '" + this + "' can not operate on " + getLevelDesc(level) + ".");
        }
        super.resolveLevel(level - 1);
    }
Constructs a new instance of this class.
container-search/src/main/java/com/yahoo/search/grouping/request/EachOperation.java