List<String> frequency = new ArrayList<>();
        Collections.addAll(frequency, "gg", "ss", "gg", "boy", "girls", "girls", "gg", "boy", "aa", "aa", "aoy", "aoy", "bb", "bb");

return words.stream().collect(Collectors.groupingBy(Function.identity(),Collectors.counting()))
                .entrySet().stream().filter(entry -> entry.getValue()>1)
                .sorted(Comparator.comparingInt(e -> e.getKey().length())).limit(5).map(Map.Entry::getKey).collect(Collectors.toList());

aa
gg
aoy
boy
girls

bb
aa
gg
aoy
boy