Java comm(1) implementation

Comm.java

import java.util.List;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterators;
import com.google.common.collect.PeekingIterator;

public class Comm {
    public static class Result {
        public final ImmutableList<Integer> only1;
        public final ImmutableList<Integer> only2;
        public final ImmutableList<Integer> both;

        public Result(ImmutableList<Integer> only1, ImmutableList<Integer> only2,
                ImmutableList<Integer> both) {
            this.only1 = only1;
            this.only2 = only2;
            this.both = both;
        }
    }

    public static Result comm(List<Integer> list1, List<Integer> list2) {
        ImmutableList.Builder<Integer> only1 = ImmutableList.builder(),
                only2 = ImmutableList.builder(), both = ImmutableList.builder();
        PeekingIterator<Integer> iter1 = Iterators.peekingIterator(list1.iterator()),
                iter2 = Iterators.peekingIterator(list2.iterator());
        while (true) {
            if (!iter1.hasNext()) {
                only2.addAll(iter2);
                break;
            }
            if (!iter2.hasNext()) {
                only1.addAll(iter1);
                break;
            }
            int x = iter1.peek(), y = iter2.peek();
            if (x < y) {
                only1.add(x);
                iter1.next();
            } else if (y < x) {
                only2.add(y);
                iter2.next();
            } else {
                both.add(x);
                iter1.next();
                iter2.next();
            }
        }
        return new Result(only1.build(), only2.build(), both.build());
    }

    public static void main(String... args) {
        Result result = comm(ImmutableList.of(1, 2, 3, 5, 8, 13),
                ImmutableList.of(2, 3, 5, 7, 11, 13));
        System.out.printf("Only in list 1: %s%n" +
                          "Only in list 2: %s%n" +
                          "In both lists: %s%n",
                result.only1,
                result.only2,
                result.both);
    }
}