code: public NotificationArea createNotificationArea(RESTRequest request, String basePath, NotificationSettings notificationSettings) {
          //Cleanup old clients
          cleanUp(request);
  
          //Fetch a new ID
          int clientID = getNewClientID();
  
          //Make the new inbox and insert into map
          ClientNotificationArea newInbox = new ClientNotificationArea(notificationSettings.deliveryInterval, notificationSettings.inboxExpiry, clientID);
  
          //Don't need to use "putIfAbsent" here because the key is guaranteed to be unique
          inboxes.put(clientID, newInbox);
  
          //Create the notification area to be returned to the client
          NotificationArea newArea = new NotificationArea();
          newArea.clientURL = basePath + clientID;
          newArea.inboxURL = newArea.clientURL + "/inbox";
          newArea.registrationsURL = newArea.clientURL + "/registrations";
          newArea.serverRegistrationsURL = newArea.clientURL + "/serverRegistrations";
  
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "Created notification area for client ID " + clientID);
          }
  
          return newArea;
      }
docs: Creates a new clientID, inbox and NotificationArea