Exclusive Sponsorship / Enable exclusivity

[jh...@boostr.com]

Hello, 

I see there is this field:

When I enable this in the UI, and then push an up to the line item via API, I keep reseting this to false. So I'm trying to identify what field this is in the API docs, so that I can get a GET to get the existing value and then send it back on the PUT. 

Can you point me to what field this is?