Case modification in the substitution?

Hello,

According to ORO API docs, Perl5Substitution supports case
modification like \u or \l. I can't get it work:

  PatternMatcher matcher = new Perl5Matcher();
  Perl5Compiler compiler = new Perl5Compiler();
  Substitution s = new Perl5Substitution("\\u$1");
  Pattern pattern = compiler.compile("(.*)");
  System.out.println(Util.substitute(matcher, pattern, s, "foo"));

I want it see:

  Foo

but it prints:

  \ufoo

What do I badly? (I use ORO 2.0.5.)

-- 
Best regards,
 Daniel Dekany