如何在oat++端点上使用MIME代码进行响应

#include "oatpp/web/server/api/ApiController.hpp"
#include "oatpp/web/server/handler/ErrorHandler.hpp"
#include "oatpp/network/Server.hpp"
#include "oatpp/network/tcp/server/ConnectionProvider.hpp"

#include "oatpp/core/macro/component.hpp"

#include <iostream>

#include <oatpp/web/server/HttpConnectionHandler.hpp>
#include <oatpp/web/server/HttpRouter.hpp>
#include <oatpp/core/macro/codegen.hpp>
#include <oatpp/parser/json/mapping/ObjectMapper.hpp>
#include <oatpp/web/protocol/http/outgoing/ResponseFactory.hpp>
#include <oatpp/web/protocol/http/Http.hpp>

class MyController : public oatpp::web::server::api::ApiController {
public:
  MyController(const std::shared_ptr<ObjectMapper>& objectMapper)
    : oatpp::web::server::api::ApiController(objectMapper)
  {}

  ENDPOINT_INFO(root) {
    info->summary = "Root endpoint";
    info->addResponse<Object<oatpp::Object>>("text/plain");
    info->addResponse<Object<oatpp::Object>>("application/json");
  }
  ENDPOINT("GET", "/", root) {
    const char* message = "Hello, World!";
    auto response = createResponse(Status::CODE_200, message);
    response->putHeader(Header::CONTENT_TYPE, "text/plain");
    return response;
  }
};

typedef oatpp::web::server::HttpConnectionHandler HttpConnectionHandler;

void run() {
  oatpp::base::Environment::init();
  
  oatpp::base::Environment::initComponents<oatpp::web::server::HttpRouter>();
  
  OATPP_COMPONENT(std::shared_ptr<ObjectMapper>, objectMapper);
  auto router = oatpp::base::Environment::get().getComponents().getDependency<oatpp::web::server::HttpRouter>();

  auto myController = std::make_shared<MyController>(objectMapper);
  myController->addEndpointsToRouter(router);

  auto connectionProvider = oatpp::network::tcp::server::ConnectionProvider::createShared({ "localhost", 8000 });

  oatpp::network::Server server(connectionProvider, connectionProvider);

  OATPP_COMPONENT(std::shared_ptr<HttpConnectionHandler>, connectionHandler);
  server.addConnectionHandler(connectionHandler);

  OATPP_COMPONENT(std::shared_ptr<oatpp::network::ServerConnectionProvider>, serverConnectionProvider);
  oatpp::base::Environment::get().getLogger()->info("Server running on port %s", serverConnectionProvider->getProperty("port").getData());

  server.run();
  oatpp::base::Environment::destroy();
}

int main() {
  run();
  return 0;
}