clear list from duplicate individual elements

clearListFromDuplicateIndividualElements.java

private List<?> clearListFromDuplicates(List<?> list1) {

        Map<String, ?> cleanMap = new LinkedHashMap<String, ?>();
        for (int i = 0; i < list1.size(); i++) {
            cleanMap.put(list1.get(i)./**existing, double element*/, list1.get(i));
        }
        List<?> list = new ArrayList<?>(cleanMap.values());
        return list;
}