session-android/res/drawable/conversation_item_received_shape_dark.xml

<?xml version="1.0" encoding="UTF-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item>
        <shape  android:shape="rectangle">
            <solid android:color="#ff222222" />
            <corners android:radius="@dimen/conversation_item_corner_radius" />
        </shape>
    </item>

    <item android:bottom="@dimen/conversation_item_drop_shadow_dist">
        <shape xmlns:android="http://schemas.android.com/apk/res/android">
            <solid android:color="#ff333333" />
            <!--stroke android:width="0.5dp" android:color="#03000000" /-->
            <corners android:radius="@dimen/conversation_item_corner_radius" />
        </shape>
    </item>

</layer-list>