Characters like 'é' can be expressed either as a single code point or as a cluster of the letter 'e' and a combining
accent mark. Without the CANON_EQ flag, a regex will only match a string in which the characters are expressed in the same way.
Noncompliant code example
String s = "e\u0300";
Pattern p = Pattern.compile("é|ë|è"); // Noncompliant
System.out.println(p.matcher(s).replaceAll("e")); // print 'è'
Compliant solution
String s = "e\u0300";
Pattern p = Pattern.compile("é|ë|è", Pattern.CANON_EQ);
System.out.println(p.matcher(s).replaceAll("e")); // print 'e'
