Encoding Problem when calculating the Lenght of the Response contentLenght

Hi, 

the servlet responses are cut off when containing utf8 charachters like 'ä', 'ö', ...

I've noticed that you already fixed this issue in your current master. Could you release a new Version with this fix? This is a show stopper for us.

```
response.setContentLength(responseContent.getBytes(StandardCharsets.UTF_8).length);
```

Best regards,
Simon Jakuobwski