JAVA

error: package android.support.v4.content does not exist import android.support.v4.content.FileProvider; ^

import androidx.core.content.FileProvider;

: error: package android.support.v4.content does not exist import android.support.v4.content.ContextCompat;

This is likely happening because one of your dependencies is now using AndroidX
instead of the support library. This means all dependencies need to use it, but
this one hasn't been upgraded yet.

There is a tool which can handle the conversion for you, but it's currently 
experimental.

https://github.com/mikehardy/jetifier#usage-for-source-files