public void testEscapeXML() {
   assertEquals("", StringUtils.escapeXML(null));
   assertEquals("", StringUtils.escapeXML(""));
   assertEquals("abc&def", StringUtils.escapeXML("abc&def"));
   assertEquals("abc"def'", StringUtils.escapeXML("abc\"def'"));
   assertEquals("&lt;&gt;", StringUtils.escapeXML("<>"));
 }