Creating a rectangle shape with only two rounded edges

<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" android:padding="10dp">
<solid android:color="#FFFFFF"/>
<corners 
android:bottomRightRadius="0dp"
android:bottomLeftRadius="0dp"
android:topLeftRadius="15dp"
android:topRightRadius="15dp"/>
</shape>

This code is just working (since?) Android version 2.2. Referring to the documentation, the code should look like the following:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" android:padding="10dp">
<solid android:color="#FFFFFF"/>
<corners 
android:radius="2dp"
android:bottomRightRadius="0dp"
android:bottomLeftRadius="0dp"
android:topLeftRadius="15dp"
android:topRightRadius="15dp"/>
</shape>