I have `AppBarLayout` and `Toolbar` in acitivty and `TabLayout` into my Fragment. How can I set my toolbar shadow to zero so it would be smooth place between toolbar and tablayout?

```
<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:elevation="0dp"
    android:theme="@style/SDK.Theme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:minHeight="?attr/actionBarSize"
        app:elevation="0dp"
        local:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        local:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

```