for (int i = 0; i < numElements; i++) {
String keyString = Integer.toHexString(i);
byte[] key = keyString.getBytes();
assertEquals(tree.lookup(key), map1.get(keyString));
}
// create a new overlay
int snap1 = tree.newOverlay();
final SortedMap<String, byte[]> map2 = new TreeMap<String, byte[]>(map1);