@SuppressWarnings({"rawtypes", "unchecked"})
    public static int compare(Collection<? extends Comparable> first, Collection<? extends Comparable> second) {
        if (first.size() < second.size()) {
            return -1;
        }
        if (first.size() > second.size()) {
            return 1;
        }

        //sizes are equal, compare contents
        Iterator<? extends Comparable> firstIt = first.iterator();
        Iterator<? extends Comparable> secondIt = second.iterator();

        while (firstIt.hasNext()) {
            // FIXME: unchecked casting
            Comparable itemFirst = firstIt.next();
            Comparable itemSecond = secondIt.next();
            int comp = itemFirst.compareTo(itemSecond);
            if (comp != 0) {
                return comp;
            }
            //values are equal, continue...
        }

        //we haven't returned yet; contents must be equal:
        return 0;
    }
Compare the arguments. Shorter Collections are always considered
smaller than longer Collections. For Collections of equal lengths, the elements
are compared one-by-one. Whenever two corresponding elements in the
two Collections are non-equal, the method returns. If all elements at
corresponding positions in the two Collections are equal, the Collections
are considered equal.

@param first a Collection of Comparables to be compared
@param second a Collection of Comparables to be compared
@return 0 if the arguments are equal, -1 if the first argument is smaller, 1 if the second argument is smaller
@throws NullPointerException if any of the arguments are null
vespajlib/src/main/java/com/yahoo/collections/CollectionComparator.java