Understanding about first_open event

[vegeta]

Hi there !

I am confused with `first_open` event in FireBase.

Here is the document :

first_open

the first time a user launches an app after installing or re-installing it. This event is not triggered when a user downloads the app onto a device, but instead when he or she first uses it. To see raw download numbers, look in Google Play Developer Console or in iTunesConnect.

However some people from Google said that : 

The last important distinction is that when existing users migrate to the new version of your app which includes Firebase, they will log a first_open event. And so, even though they are not new users, they log a first_open.

As my understanding, If we update version app then start app again first_open will be logged ?  Is that correct ???

[Mahesh Khambadkone]

It gets triggered if the user installs the game or re-installs it.

It gets triggered on an update, ONLY if the previous version did not previously have Firebase