Android app. "identify" and led blinking before the provisioning process


I m working with mesh demo:

In Android app we can press "identify" and after that Thingy's led is blinking very fast. Then we can start provisioning. My question is how to start identification proces?

Should I change some characteristic?

In firmware I found this function:

as I understand this function is calling after user pressed "identify" on his smartphone's screen. But how this mehanism works?