Co oznacza dwukropek w Javie?

Co oznacza dwukropek w Javie? Mam to:

public static List<String> findAllAnagrams(List<String> words) {
    List<String> result = new LinkedList<String>();
    for(String i : words){
        for (String j : words){
            if (result.contains(i)) {
                break;
            }
            else if (i == j) {

            } else {
                if (areAnagrams(i,j)){
                    result.add(i);
                    System.out.println(result);
                }
            }
        }
    }          
    return result;
}

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