Google Chat Bot: Bot reply not seen by both people

Question

I have created a chat bot for google chat to our gsuite. When I type @DadJokes it returns random dadjoke from an API

Problem is that only I can see the returned joke and I cannot find info about this in the documentation.

Can anyone navigate me to the right path?

Thank you

function getDadJoke() {
  var response = UrlFetchApp.fetch('https://icanhazdadjoke.com/', {
    method: 'get',
    headers: { 'Accept': 'text/plain' },
    contentType: 'plain/text',
  });
  
 return response.getContentText();
}

/**
 * Responds to a MESSAGE event in Hangouts Chat.
 *
 * @param {Object} event the event object from Hangouts Chat
 */
function onMessage(event) {
  console.log(getDadJoke());
  return { "text": getDadJoke() };
}

/**
 * Responds to an ADDED_TO_SPACE event in Hangouts Chat.
 *
 * @param {Object} event the event object from Hangouts Chat
 */
function onAddToSpace(event) {
  return { "text": getDadJoke() };
}

/**
 * Responds to a REMOVED_FROM_SPACE event in Hangouts Chat.
 *
 * @param {Object} event the event object from Hangouts Chat
 */
function onRemoveFromSpace(event) {
  console.info("Bot removed from ",(event.space.name ? event.space.name : "this chat"));
}

UPDATE

I got it working using async messages, but now others receive the joke sooner then my own message where I typed @DadJokes. So that means i type @DadJokes, chat participants recieve the joke from bot, then they receive my message @DadJokes

function getDadJoke() {
  var response = UrlFetchApp.fetch('https://icanhazdadjoke.com/', {
    method: 'get',
    headers: { 'Accept': 'text/plain' },
    contentType: 'plain/text',
  });
  
 return response.getContentText();
}

function sendDadJoke(spaceId) {
 
   var service = OAuth2.createService('chat')
      .setTokenUrl('https://accounts.google.com/o/oauth2/token')
      .setPrivateKey(SERVICE_ACCOUNT_PRIVATE_KEY)
      .setClientId(SERVICE_ACCOUNT_EMAIL)
      .setPropertyStore(PropertiesService.getUserProperties())
      .setScope(SCOPE);
  
  if (!service.hasAccess()) {
    Logger.log('Authentication error: %s', service.getLastError());
    return;
  }
  
  var url = 'https://chat.googleapis.com/v1/' + spaceId + '/messages';
  
  UrlFetchApp.fetch(url, {
    method: 'post',
    headers: { 'Authorization': 'Bearer ' + service.getAccessToken() },
    contentType: 'application/json',
    payload: JSON.stringify({ "text": getDadJoke() }),
  });
  
}


/**
 * Responds to a MESSAGE event in Hangouts Chat.
 *
 * @param {Object} event the event object from Hangouts Chat
 */
function onMessage(event) {
  
  sendDadJoke(event.space.name);
  
  return {"message": "Okay here it comes!"};
}

/**
 * Responds to an ADDED_TO_SPACE event in Hangouts Chat.
 *
 * @param {Object} event the event object from Hangouts Chat
 */
function onAddToSpace(event) {
 
  sendDadJoke(event.space.name);
  
  return {"message": "Okay here it comes!"};
}

/**
 * Responds to a REMOVED_FROM_SPACE event in Hangouts Chat.
 *
 * @param {Object} event the event object from Hangouts Chat
 */
function onRemoveFromSpace(event) {
  console.info("Bot removed from ",(event.space.name ? event.space.name : "this chat"));
}