Implement expandable and collapsible notification android - android-push-notification

Question

I have applied push notifications in my App. Now it is expandable only if there is no other notification (and it did not contain an icon to expand, that should be). I want this to be expandable like WhatsApp notifications having an expandable icon as shown in the Screenshot(2nd notification is from my app). I applied a different style but can't achieve it, please help me to do so. The device on which I am testing notifications is Redmi Note 10(android 12). Thanks in advance.
This is the Screenshot of what I want
Below is the code of my notification:
'''
public class FirebaseMessagingService extends
com.google.firebase.messaging.FirebaseMessagingService {
NotificationManager mNotificationManager;
#Override
public void onMessageReceived(RemoteMessage remoteMessage) {
super.onMessageReceived(remoteMessage);
try {
// playing audio and vibration when user send request
Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), notification);
r.play();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
r.setLooping(false);
}
// vibration
Vibrator v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
long[] pattern = {100, 300, 300, 300};
v.vibrate(pattern, -1);
Bitmap bitmapFactory=BitmapFactory.decodeResource(getApplicationContext().getResources(),
R.mipmap.ic_launcher);
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, "CHANNEL_ID");
Intent resultIntent = null;
if (FirebaseAuth.getInstance().getCurrentUser()!=null){
resultIntent=new Intent(this, MainActivity.class);
}else {
resultIntent=new Intent(this,SplashScreen.class);
}
PendingIntent pendingIntent;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
pendingIntent = PendingIntent.getActivity(this,
1, resultIntent, PendingIntent.FLAG_UPDATE_CURRENT |
PendingIntent.FLAG_IMMUTABLE);
}else {
pendingIntent = PendingIntent.getActivity(this,
1, resultIntent, PendingIntent.FLAG_UPDATE_CURRENT);
}
builder.setSmallIcon(R.mipmap.ic_launcher);
builder.setStyle(new NotificationCompat.BigPictureStyle().bigPicture(bitmapFactory));
builder.setContentTitle(remoteMessage.getNotification().getTitle());
builder.setContentText(remoteMessage.getNotification().getBody());
builder.setContentIntent(pendingIntent);
builder.setStyle(new
NotificationCompat.BigTextStyle().bigText(remoteMessage.getNotification().getBody()));
builder.addAction(R.mipmap.ic_launcher,"Open App",pendingIntent);
builder.setAutoCancel(false);
builder.setPriority(Notification.PRIORITY_MAX);
mNotificationManager = (NotificationManager)
getApplicationContext().getSystemService(Context.NOTIFICATION_SERVICE);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
{
String channelId = "Your_channel_id";
NotificationChannel channel = new NotificationChannel(
channelId,
"Channel human readable title",
NotificationManager.IMPORTANCE_HIGH);
mNotificationManager.createNotificationChannel(channel);
builder.setChannelId(channelId);
}
mNotificationManager.notify(100, builder.build());
}catch (Exception e){
}
}
#Override
public void onMessageSent(#NonNull String msgId) {
Toast.makeText(this, "Notification sent successfully", Toast.LENGTH_SHORT).show();
super.onMessageSent(msgId);
}
#Override
public void onSendError(#NonNull String msgId, #NonNull Exception exception) {
Toast.makeText(this, "Sending error: "+exception.getMessage(), Toast.LENGTH_SHORT).show();
super.onSendError(msgId, exception);
}
}
'''