is there limit for android group notification?

Question

I have a question for group notifications. I want to use group notification to package the notifications. Before I notify the single notification , i will notify a groupNotifcation. But i found that the packed notification numbers is limited to 8, the newst comes, the oldest cancel. I don't know its my mistake or system restriction.

This is my code. groupNotificationChannelId is a constant.

NotificationCompat.Builder builder = new NotificationCompat.Builder(service, channelId);
initBuilder(builder);
builder.setGroup("A");
builder.setDefaults(Notification.DEFAULT_ALL);
Notification notification = builder.buide();
if (notificationCount >0 ) {
        summaryBuilder.setLargeIcon()
            .setSmallIcon()
            .setColor()
            .setContentTitle()
            .setContentText()
            .setStyle()
            .setGroup("A")
            .setGroupSummary(true)
            .setAutoCancel(true);      
    summaryBuilder.setDeleteIntent();
    summaryBuilder.setContentIntent();
    notificationManager.notify(groupNotificationChannelId, summaryBuilder.build());
}
notificationManager.notify((int) (System.currentTimeMillis() / 1000), notification);