From http://www.jwz.org/xscreensaver/xscreensaver-5.31.tar.gz

[xscreensaver] / android / project / xscreensaver / res / xml / hilbert.xml

<?xml version="1.0" encoding="utf-8"?>
<wallpaper xmlns:android="http://schemas.android.com/apk/res/android"
   android:description="@string/hilbert_description"
   android:settingsActivity="org.jwz.xscreensaver.gen.HilbertSettings"
   android:thumbnail="@drawable/hilbert" />