code: public OutputStream outputStream(String contentType, Map<String, String> headers, int status) {
          Result result = ResultBuilder.noBody(status).contentType(contentType);
          headers.entrySet().forEach(header -> result.addHeader(header.getKey(), header.getValue()));
          setControllerResult(result);
          
          try {
              //return context.responseOutputStream(); //TODO not possible, is it?
              return context.responseOutputStream(result);
          } catch(Exception e) {
              throw new ControllerException(e);
          }
      }
docs: Use to send raw data to HTTP client.
  
  @param contentType content type
  @param headers set of headers.
  @param status status.
  @return instance of output stream to send raw data directly to HTTP client.