public void test_findCommonOverlap() {
   assertEquals(0, StringUtilities.findCommonOverlap("", "abcd"));
   assertEquals(3, StringUtilities.findCommonOverlap("abc", "abcd"));
   assertEquals(0, StringUtilities.findCommonOverlap("123456", "abcd"));
   assertEquals(3, StringUtilities.findCommonOverlap("123456xxx", "xxxabcd"));
 }