I researched about this and found out that addAction (int icon, CharSequence title, PendingIntent intent)
is deprecated, so I used addAction (Notification.Action action)
. In both the cases, icon cant be seen.
NotificationCompat.Action action = new NotificationCompat.Action.Builder(R.drawable.ic_share, "", pendingIntent).build();
notificationBuilder.addAction(action);
The text seems to be working though, but I have left it blank, hence there is an empty space below the main image, where icon is supposed to be displayed
This is not an error, but a change in the design with Android Nougat. Icons defined by addAction (Notification.Action action) are not any more displayed by devices. They still are required for older devices and Android Wear devices!
Quoting android developers google blog