StringEscapeUtils.escapeXml(str) does not support supplemental characters.

Hello.

StringEscapeUtils.escapeXml(str) escapes Unicode characters greater than 0x7f to their numerical
u equivalent:

String str = StringEscapeUtils.escapeXml("\uD84C\uDFB4");
System.out.println(str);
//��

But, the output should be 𣎴.

According to W3C document "Using character escapes in markup and CSS," We must use the single, code point value for supplemental character.
http://www.w3.org/International/questions/qa-escapes

In fact, �� is not rendered correctly in some web browsers e.g., Firefox 5.0 and Chrome 12.0.