hardware/drawable-anydpi-v21/ic_dock_black_24dp.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"
        android:width="24dp"
        android:height="24dp"
        android:viewportWidth="24.0"
        android:viewportHeight="24.0">
    <path
        android:fillColor="#FF000000"
        android:pathData="M8,23h8v-2L8,21v2zM16,1.01L8,1c-1.1,0 -2,0.9 -2,2v14c0,1.1 0.9,2 2,2h8c1.1,0 2,-0.9 2,-2L18,3c0,-1.1 -0.9,-1.99 -2,-1.99zM16,15L8,15L8,5h8v10z"/>
</vector>