транслировать в Java 8 stream

public static List<Pair<String, String>> getCityAssignedCodeForProvider(Set<String> departureAssignedCodes, Set<String> arrivalAssignedCodes) { 
        List<Pair<String, String>> pairList = new ArrayList<>(); 
        for (String departure : departureAssignedCodes) { 
            String[] splitDeparture = departure.split(","); 
            for (String arrival : arrivalAssignedCodes) { 
                    String[] splitArrival = arrival.split(","); 
                    for (String departureSplitItem : splitDeparture) { 
                        for (String arrivalSplitItem : splitArrival) { 
                            pairList.add(new Pair<>(departureSplitItem, arrivalSplitItem)); 
                        } 
                    } 
            } 
        } 
        return pairList; 
}