public final class Person {

    private final String  name;
    private final Country country;

    @BsonCreator
    public Person(
            @BsonProperty("name") String name,
            @BsonProperty("country") Country country) {

        this.name = name;
        this.country = country;
    }

    @BsonId
    public String getName() {
        return name;
    }

    public Country getCountry() {
        return country;
    }

    public enum Country {
        IRELAND,
        POLAND
    }
}

MongoCollection<Person> collection = new MongoClient()
        .getDatabase("database")
        .getCollection("people", Person.class)
        .withCodecRegistry(fromRegistries(
                getDefaultCodecRegistry(),
                fromProviders(
                        PojoCodecProvider
                                .builder()
                                .automatic(true) // note the automatic POJO support
                                .build()
                )
        ));

Person person = collection
        .find(eq("country", POLAND))
        .first();