Angular upgrade

	- Upgraded Angular from 14 to 15 version.

Change-Id: I2339a04020153cbc9ed7a14bfe8e0aa265e507da
Signed-off-by: SANDHYA.JS <sandhya.j@tataelxsi.co.in>
diff --git a/src/app/AppComponent.ts b/src/app/AppComponent.ts
index 1c5886a..26d7aab 100644
--- a/src/app/AppComponent.ts
+++ b/src/app/AppComponent.ts
@@ -19,13 +19,12 @@
 /**
  * @file App Components
  */
-import { isNullOrUndefined } from 'util';
 import { Component, HostListener, Injector } from '@angular/core';
 import { NgbModal } from '@ng-bootstrap/ng-bootstrap';
 import { DEFAULT_INTERRUPTSOURCES, Idle } from '@ng-idle/core';
 import { AuthenticationService } from 'AuthenticationService';
 import { DeviceCheckService } from 'DeviceCheckService';
-import { SharedService } from 'SharedService';
+import { SharedService, isNullOrUndefined } from 'SharedService';
 
 /**
  * Creating component