How to make all textual response as UTF-8 on Jooby

import io.jooby.Jooby;
import io.jooby.MediaType;
import java.nio.charset.StandardCharsets;

public class App extends Jooby {

  {
    // use Decorator.
    decorator(next -> ctx -> {
      // get response content-type.
      final MediaType responseType = ctx.getResponseType();
      // if content-type is text-specific
      if(responseType.isTextual())
      // override response type with current media type and always use UTF-8 charset!
        ctx.setResponseType(responseType, StandardCharsets.UTF_8);
      // pipe next response procedure.
      return next.apply(ctx);
    });

    get("/", ctx -> "Abc가나다漢文");
  }

  public static void main(final String[] args) {
    runApp(args, App::new);
  }
}