EntranceChecker.java

public class EntranceChecker {
    private final Set<String> names;
    public EntranceChecker(Set<String> names) {
        this.names = names;
    }

    boolean isInTheGuestList(Person person) {
        if(person == null) {
            return true;
        }
       
        return names.contains(person.getName());
    }
}