laravel-firebase-sync | Eloquent models with a Firebase Realtime Database | Database library

I'm using the Laravel-firebase-sync package. In their docs they say:

If you need more control over the data that gets synchronized with Firebase, you can override the getFirebaseSyncData of the SyncsWithFirebase trait and let it return the array data you want to send to Firebase.

But I can't locate that method. I want to know if someone that has already used this package know a way to custom the object that get syncronized.

Why I want to do this? Well, I'm using Laravel as a backend, so in one model I have Restaurant, there I have a field called min_price_range that is an integer that goes from 1-4. But before I return it I transform it to $-$$$$. So I need to do this before the object gets sync in Firebase. Otherwise the objects won't match between Laravel and Firebase databases (when consumed in mobile client apps).

PD1: I've already test it and it doesn't work. It just sync the hole object (the fields of the visible array).

PD2: Yes, I've already opened an issue in the project repository but they seem to response a couple months after.

Thanks in advance.