StringEscapeUtils.escapeXml(input) outputs wrong results when an input contains characters in Supplementary Planes.

Hello.

I use StringEscapeUtils.escapeXml(input) to escape special characters for XML.
This method outputs wrong results when input contains characters in Supplementary Planes.

String str1 = "\uD842\uDFB7" + "A";
String str2 = StringEscapeUtils.escapeXml(str1);

// The value of str2 must be equal to the one of str1,
// because str1 does not contain characters to be escaped.
// However, str2 is diffrent from str1.

System.out.println(URLEncoder.encode(str1, "UTF-16BE")); //%D8%42%DF%B7A
System.out.println(URLEncoder.encode(str2, "UTF-16BE")); //%D8%42%DF%B7%FF%FD

The cause of this problem is that the loop to translate input character by character is wrong.
In CharSequenceTranslator.translate(CharSequence input, Writer out),
loop counter "i" moves from 0 to Character.codePointCount(input, 0, input.length()),
but it should move from 0 to input.length().