On Cancel and Fill logic in SampleOnOrderUpdate

[binwang2]

As i read the code for SampleOnOrderUpdate, the logic for "
OnExecution(IExecution execution)" section has one condition as the following:
if (execution.Order.OrderState == OrderState.Filled || execution.Order.OrderState == OrderState.PartFilled || (execution.Order.OrderState == OrderState.Cancelled && execution.Order.Filled > 0))

I have a curious question on the underlined part: under what condition can an order be cancelled and filled at the same time?

[NinjaTrader_JoshP]

Cancelled after a partial fill.