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

Hello.

I m working with mesh demo: https://github.com/NordicPlayground/thingy52-mesh-provisioning-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?

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