Update XmlObjectSerializer.php
Update XmlObjectSerializer.php

https://github.com/intuit/QuickBooks-V3-PHP-SDK/commit/b2dd4e3f05ff01298f8efaa3e1c74e18ddd378cd#commitcomment-41081132
intuit/QuickBooks-V3-PHP-SDK,intuit/QuickBooks-V3-PHP-SDK,intuit/QuickBooks-V3-PHP-SDK