{
public void testMaskingForFindPrefix() throws Exception
{
BijectiveNsMap nsMap = BijectiveNsMap.createEmpty();
nsMap.addMapping("ns", "abc");
assertEquals("ns", nsMap.findPrefixByUri("abc"));
// and then let's mask it
nsMap = nsMap.createChild();
nsMap.addMapping("ns", "xyz");
String uri = nsMap.findPrefixByUri("abc");
if (uri != null) {