createAuthenticationContext(authority: string, validateAuthority: boolean = true) {
   let authContext: any;
   if (checkAvailability(MSAdal.getPluginRef(), null, MSAdal.getPluginName()) === true) {
     authContext = new (MSAdal.getPlugin()).AuthenticationContext(authority);
   }
   return new AuthenticationContext(authContext);
 }

  /**
   * Creates a new instance of FlurryAnalyticsObject
   * @param options {FlurryAnalyticsOptions} options
   * @return {FlurryAnalyticsObject}
   */
  create(options: FlurryAnalyticsOptions): FlurryAnalyticsObject {

    let instance: any;

    if (checkAvailability(FlurryAnalytics.pluginRef, null, FlurryAnalytics.pluginName) === true) {
      instance = new (window as any).FlurryAnalytics(options);
    }

    return new FlurryAnalyticsObject(instance);

  }

            switchMap(() => {
                /**
                 * Native HTTP Cordova plugin doesn't like local requests
                 */
                const isExternalRequest = checkExternalRequest(req);

                if (
                    isExternalRequest &&
                    checkAvailability('cordova.plugin.http') === true
                ) {
                    return this.cordovaHttpBackend.handle(req);
                } else {
                    return this.fallbackBackend.handle(req);
                }
            }),

 constructor(title: string, options: LocalNotificationOptions) {
   if (checkAvailability(PhonegapLocalNotification.pluginRef, null, PhonegapLocalNotification.pluginName) === true) {
     this._objectInstance = new Notification(title, options);
   }
 }

 constructor(options: PushOptions) {
   if (checkAvailability('PushNotification', 'init', 'PushNotification') === true) {
     this._objectInstance = window.PushNotification.init(options);
   }
 }

 constructor() {
   if (checkAvailability('navigator.contacts', 'create', 'Contacts') === true) {
     this._objectInstance = navigator.contacts.create();
   }
 }