Write a function which takes 2 lists (List<Group>) as arguments and compares 2 lists by ignoring case and returns the count of mismatched groups, extra groups in first list and extra groups in second list

public class GroupComparator {
    public static Pair<Integer, Pair<List<String>, List<String>>> compareGroups(List<String> group1, List<String> group2) {
        group1 = group1.stream().map(groupName -> groupName.toLowerCase()).collect(Collectors.toList());
        group2 = group2.stream().map(groupName -> groupName.toLowerCase()).collect(Collectors.toList());

        List<String> extraGroupInFirst = new ArrayList<>();
        List<String> extraGroupInSecond = new ArrayList<>();
        int mismatchedGroups = 0;

        for (String group : group1) {
            if (!group2.contains(group)) {
                extraGroupInFirst.add(group);
            }
        }

        for (String group : group2) {
            if (!group1.contains(group)) {
                extraGroupInSecond.add(group);
            }
        }

        for (String group : group1) {
            if (extraGroupIn