public Contact(String firstName, String lastName, PhoneNumber... phoneNumbers) {
		super(NextIdGenerator.getNextId(Contact.class));
		this.firstName = firstName;
		this.lastName = lastName;
		this.phoneNumbers = hasPhoneNumbers(phoneNumbers) ? null : Lists.newArrayList(Arrays.asList(phoneNumbers));
		ensureRequiredFieldsAreProvided(getMandatoryFields());
	}