Constructor: sendMessageCancelAction
Invalidate all previous action updates. E.g. when user deletes entered text or aborts a video upload.
Type: SendMessageAction
Example:
 $sendMessageCancelAction = ['_' => 'sendMessageCancelAction']; 
Invalidate all previous action updates. E.g. when user deletes entered text or aborts a video upload.
 $sendMessageCancelAction = ['_' => 'sendMessageCancelAction'];