The Android Gradle plugin provides the following global flags that you
can set in your gradle.properties file:android.useAndroidX: When set to true, this flag indicates that you
want to start using AndroidX from now on. If the flag is absent,
Android Studio behaves as if the flag were set to false.android.enableJetifier: When set to true, this flag indicates that you
want to have tool support (from the Android Gradle plugin) to
automatically convert existing third-party libraries as if they were
written for AndroidX. If the flag is absent, Android Studio behaves as
if the flag were set to false.
To enable jetifier, add those two lines to your gradle.properties file:
android.useAndroidX=true
android.enableJetifier=true