/**
* @param postalCode Postal code of the card.
* @return {@link com.braintreepayments.api.models.CardBuilder}
*/
public CardBuilder postalCode(String postalCode) {
BillingAddress billingAddress = new BillingAddress();
billingAddress.setPostalCode(postalCode);
mCard.setBillingAddress(billingAddress);
return this;
}