What the purpose of setGroup() in Notification.Builder?

Question

I have a some troubles with understanding of goal of setGroup() method.

As docs said :

...Grouped notifications may display in a cluster or stack on d

Answer 1

setGroupSummaryis there to support grouped notifications on devices before Nougat. It replaces the single notifications with 1 summary notification. On Nougat+ the system creates a normal group, which is not your notification with setGroupSummary(true)