thrhrthrth

public static Map<Officer, Spaceship> getHighestRankingOfficerPerShip(Collection<Spaceship> fleet) {
        Map<Officer, Spaceship> officersMap = new HashMap<Officer, Spaceship>();
        for (Spaceship ship: fleet) {
            Stream<Officer> officers = ship.getCrewMembers().stream().filter(member -> member instanceof Officer).map(member -> (Officer) member);
            Officer seniorOfficer = officers.max((officer1, officer2) -> officer1.getRank().compareTo(officer2.getRank())).get();
            officersMap.put(seniorOfficer, ship);
        }
        return officersMap;
    }