Class AccessoryWidget

const widget = CardService.newButtonSet()
    .addButton(CardService.newImageButton()
      .setIcon(CardService.Icon.PHONE)
      .setOnClickAction(CardService.newAction()
        .setFunctionName("phone")))
    .addButton(CardService.newTextButton()
      .setText("Robot")
      .setIconUrl("https://developers.google.com/chat/images/quickstart-app-avatar.png")
      .setOnClickAction(CardService.newAction()
        .setFunctionName("robot")));

const accessoryWidget = AddOnsResponseService.newAccessoryWidget()
    .addWidget(widget);