Therefore each parameter to the method gets past through an object array. To make things even more difficult, you can't just instantiate the array initially with the number of parameters to pass, and if one is not required just pass 'null'. This logic just does not work. Instead try using the ArrayList. The below code will show you how I use two methods exposed through the connector to build a purchase order with multiple line items. The lines commented is how I experimented with nulls.