¿Como añadir sombra al titulo cuando se utiliza setExpandedTitleTextAppearance?

[Alvaro Marcani]

En resumen encontré la pregunta al mismo problema que tengo en StackOverflow y espero puedan darme la solución ya que ahí nadie respondió:

I have a problem with collapsing toolbar, on expanded state I want a blurry shadow under the text, I use this code :

collapsingToolbar.setExpandedTitleTextAppearance(R.style.toolbar_text);

with :

<style name="toolbar_text">
    <item name="android:textColor">@color/white</item>
    <item name="android:shadowColor">@color/black</item>
    <item name="android:shadowDx">2</item>
    <item name="android:shadowDy">2</item>
    <item name="android:shadowRadius">4</item>
</style>

I cant change the textColor, it works but the shadow doesn't work. I have tried many different value for shadow. Is it possible to cast a shadow to the collapsed text? Because on light images the title is sometimes hard to read. Thanks !