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// String s may be user controllable
// \uFE64 is normalized to < and \uFE65 is normalized to > using NFKC
String s = "\uFE64" + "script" + "\uFE65"; 

// Validate
Pattern pattern = Pattern.compile("[<>]"); // Check for angle brackets
Matcher matcher = pattern.matcher(s);
if (matcher.find()) {
  System.out.println("found// Found black listed tag"
  throw new IllegalStateException();
} else {
  // ... 
}

// Normalize
s = Normalizer.normalize(s, Form.NFKC); 

String s = "\uFE64" + "script" + "\uFE65";

// normalize
s = Normalizer.normalize(s, Form.NFKC); 

//validate
Pattern pattern = Pattern.compile("[<>]"); 
Matcher matcher = pattern.matcher(s);
if (matcher.find()) {
  System.out.println("found // Found black listed tag"); 
  throw new IllegalStateException();
} else {
  // ... 
}