onBuildOutgoingCallNotification    
  open fun onBuildOutgoingCallNotification(builder: NotificationCompat.Builder, ringingState: RingingState, callId: StreamCallId, callDisplayName: String? = null, shouldHaveContentIntent: Boolean = true, payload: Map<String, Any?>): NotificationCompat.Builder
Intercept the notification builder and modify it before it is posted.
Parameters
builder
The notification builder.
ringingState 
The current state of ringing call, represented by RingingState
callId 
An instance of StreamCallId representing the call identifier
callDisplayName  
The name of the caller to display in the notification
shouldHaveContentIntent   
If set to true then it will launch a screen when the user will click on the notification