Generated enforcers fail to intepret length restriction

  typedef foo { 
    type string { 
      length 1; 
    } 
  } 

    private static void check_valueLength(final String value) { 
        final int length = value.length(); 
        if (length == 1) { 
            return; 
        } 
        CodeHelpers.throwInvalidLength("[[1..1]]", value); 
    } 

// U+1F31E
final String str = "�"
// Encodes as "\u0xD83C\u0xDF1E", i.e. two code units
assertEquals(2, str.length());
// The two code units together yield a single code point
assertEquals(1, str.codePointCount(0, str.length());