addListeners

// Create a listener to track downloading state updates.
val listener = InstallStateUpdatedListener { state -> 

     // Update progress indicator, request user to approve app reload
     
     if (state.installStatus() == InstallStatus.DOWNLOADING) {
          // show the progress to the User
            updateStatetoDownloading()
        }else if (state.installStatus() == InstallStatus.DOWNLOADED) {
          // After the update is downloaded, show a notification
          // and request user confirmation to restart the app.
            popupSnackbarForCompleteUpdate()
        }
}

// At some point before starting an update, register a listener for updates.
appUpdateManager.registerListener(listener)

// At some point when status updates are no longer needed,unregister the listener. 
appUpdateManager.unregisterListener(listener)