hazelcast aggregation count with filter

hzaggregation.java

public static void main(String[] args) throws InterruptedException {
        HazelcastInstance instance = Hazelcast.newHazelcastInstance(new Config());
        IMap<Integer, Person> map = instance.getMap("map");
        for (int i = 0; i < 100; i++) {
            map.put(i, new Person("name" + i, i % 10));
        }
        Supplier supplier = Supplier.all(new AgeExtractor(5));
        Aggregation aggregation = Aggregations.count();
        Long count = (Long) map.aggregate(supplier, aggregation);
        System.out.println("count:"+count);
    }

    static class AgeExtractor implements PropertyExtractor<Person, Integer>, Serializable {
        int filter;
        AgeExtractor(int age) {
            this.filter = age;
        }
        public Integer extract(Person value) {
            if(value.age == filter) {
                return value.age;
            }
            return null;
        }
    }