public Name middleName(String middleName) {
        this.middleName = middleName;
        return this;
    }
When the party is a person, the party's middle name. Use also to store multiple middle names including the patronymic, or father's, middle name.
pay-java-paypal/src/main/java/com/egzosn/pay/paypal/v2/bean/order/Name.java