public UnionPayCardBuilder mobilePhoneNumber(String mobilePhoneNumber) {
        if (TextUtils.isEmpty(mobilePhoneNumber)) {
            mMobilePhoneNumber = null;
        } else {
            mMobilePhoneNumber = mobilePhoneNumber;
        }
        return this;
    }
public UnionPayCardBuilder mobilePhoneNumber ( String mobilePhoneNumber ) { if ( TextUtils . isEmpty ( mobilePhoneNumber ) ) { mMobilePhoneNumber = null ; } else { mMobilePhoneNumber = mobilePhoneNumber ; } return this ; }
@param mobilePhoneNumber The mobile phone number to use when sending the auth code via SMS.
@return {@link com.braintreepayments.api.models.UnionPayCardBuilder}