According to Facebook's blog post, to create a CPC campaign using the new 2.4 API, we create the campaign with billing_event=LINK_CLICKS and optimization_goal=LINK_CLICKS.
https://developers.facebook.com/ads/blog/post/2015/07/08/marketing-api-v2_4/
I did that. When I look at the campaign in the Facebook Power Editor, when I look at the edit dialogue for the campaign, it says under "Optimization & Pricing" that the campaign is optimized for CPA. Two options above that is "Clicks: We'll serve your ads to people who might click on your ad (CPC)".
So I'm confused, what's the difference between CPA where the action is link clicks versus CPC? Does this have to do with the change where CPC now just counts link clicks instead of any kind of engagement? Is "CPA" correct and they're just using confusing terminology, or is the documentation wrong, or some implementation on my side or their side that's wrong?
I would post a screenshot of the Power Editor view that I'm talking about but I don't have enough reputation points.