The filterString() method in this code example normalizes the input string, validates that the input does not contain a tag, and then removes any noncharacter code points from the input string. Because input validation is performed before the removal of any noncharacter code points, an attacker can include noncharacter code points in the tag to bypass the validation checks. Modify the program to replace all noncharacter code points with Unicode FFFD before validating input. import java.text.Normalizer; import java.text.Normalizer.Form; import java.util.regex.Matcher; import java.util.regex.Pattern; public class TagFilter { public static String filterString (String str) { String s = Normalizer.normalize (str, Form.NFKC); } } // Validate input Pattern pattern Matcher matcher if (matcher.find()) { throw new IllegalArgumentException ("Invalid input"); } } = = Pattern.compile(" "); pattern.matcher(s); // Deletes noncharacter code points S = s.replaceAll("[\\p{Cn}]", ""); return s; public static void main(String[] args) { // "\uFDEF" is a noncharacter code point String maliciousInput = " "; String sb = filterString (maliciousInput); // sb = " " X