// Map is defined in a class
    private final Map<String, A> sb = new ConcurrentHashMap<>();

    public void someMethod(){
    Set<A> hSet = new HashSet<>();
    for (A a : ab){
        hSet.add(a..a...);

        // Check if all elements added to hash Set are there in a
        Map
        // if not preset add it to Map
        }
    }