Class Button

// ...

var action = CardService.newAuthorizationAction().setAuthorizationUrl('url');
CardService.newTextButton().setText('Authorize').setAuthorizationAction(action);

// ...

var action = CardService.newAction().setFunctionName('composeEmailCallback');
CardService.newTextButton()
    .setText('Compose Email')
    .setComposeAction(action, CardService.ComposedEmailType.REPLY_AS_DRAFT);

// ...

function composeEmailCallback() {
  var thread = GmailApp.getThreadById(e.threadId);
  var draft = thread.createDraftReply('This is a reply');
  return CardService.newComposeActionResponseBuilder()
      .setGmailDraft(draft)
      .build();
}

// ...

var action = CardService.newAction().setFunctionName('notificationCallback');
CardService.newTextButton().setText('Create notification').setOnClickAction(action);

// ...

function notificationCallback() {
  return CardService.newActionResponseBuilder()
      .setNotification(CardService.newNotification()
          .setText("Some info to display to user"))
      .build();
}

// ...

var action = CardService.newAction().setFunctionName('openLinkCallback');
CardService.newTextButton().setText('Open Link').setOnClickOpenLinkAction(action);

// ...

function openLinkCallback() {
  return CardService.newActionResponseBuilder()
      .setOpenLink(CardService.newOpenLink()
          .setUrl('https://www.google.com'))
      .build();
}