Toolbar with shadow without Android elevation nonsense

main_layout.xml

    <FrameLayout android:layout_width="match_parent"
                 android:layout_height="match_parent">
        <include
            layout="@layout/common_toolbar"/>

        <FrameLayout android:layout_width="match_parent"
                     android:layout_height="match_parent">

            <View android:layout_width="match_parent"
                  android:layout_height="4dp"
                  android:layout_below="@id/toolbar"
                  android:background="@drawable/toolbar_shadow"/>
                  
            // Other content, viewstub, whatever you wanna do, it goes here.
            
        </FrameLayout>
    </FrameLayout>

toolbar_shadow.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:startColor="#4b0f0f0f"
        android:endColor="@color/transparent"
        android:angle="270"/>
</shape>