Class android.app.NotificationManager

Added Methods
void createNotificationChannel(NotificationChannel)  
void createNotificationChannelGroup(NotificationChannelGroup)  
void createNotificationChannelGroups(List<NotificationChannelGroup>)  
void createNotificationChannels(List<NotificationChannel>)  
void deleteNotificationChannel(String)  
void deleteNotificationChannelGroup(String)  
NotificationChannel getNotificationChannel(String)  
List<NotificationChannelGroup> getNotificationChannelGroups()  
List<NotificationChannel> getNotificationChannels()