session-android/res/animator/appbar_elevation.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- This seems to be the dirties and the only way to set AppBar's elevation property.
    God help Android and us all.
    https://stackoverflow.com/a/45703684/3802890 -->
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <objectAnimator
            android:duration="1"
            android:propertyName="elevation"
            android:valueTo="1dp"
            android:valueType="floatType" />
    </item>
</selector>