How to return unquoted unicode characters whe parsing SQL using Apache Calcite

I'm using Apache Calcite to parse and validate some arbitrary SQL. It works for most cases but I've tried to use Unicode characters and hit some bumps.

eg;

String sql = "SELECT '®'";
SqlParser.Config config = SqlParser.configBuilder().setConfig(SqlParser.Config.DEFAULT)
                .setUnquotedCasing(Casing.UNCHANGED)
                .setQuoting(Quoting.BACK_TICK)
                .build();
        SqlParser parser = SqlParser.create(sql, config);
        SqlNode parsed;
        try {
            parsed = parser.parseQuery();
            parsed.toSqlString(MysqlSqlDialect.DEFAULT).getSql();
        } catch (Exception e) {
            // wheels fall off and catch fire
        }

This gives me SELECT u&'\00ae' which my DB doesn't want to handle. Is there some way I can configure this to return SELECT '®'? I've had a look in the SqlDialect classes and I think the issue occurs here

  public void quoteStringLiteral(StringBuilder buf, @Nullable String charsetName,
      String val) {
    if (containsNonAscii(val) && charsetName == null) {
      quoteStringLiteralUnicode(buf, val);
    } else {
      if (charsetName != null) {
        buf.append("_");
        buf.append(charsetName);
      }
      buf.append(literalQuoteString);
      buf.append(val.replace(literalEndQuoteString, literalEscapedQuote));
      buf.append(literalEndQuoteString);
    }
  }

Which doesn't seem to give me any way to avoid this behaviour.