Reading subscribers from TenantRoot model

Change-Id: Ifdf5df41faddb57ccbd3da2f7de798a8224d932e
diff --git a/src/app/service-graph/interfaces.ts b/src/app/service-graph/interfaces.ts
index b484534..0c53886 100644
--- a/src/app/service-graph/interfaces.ts
+++ b/src/app/service-graph/interfaces.ts
@@ -69,7 +69,7 @@
 }
 
 export interface IXosServiceGraphLink extends Id3Element {
-  id: number | string;
+  id: string;
   source: number;
   target: number;
   model: IXosTenantModel;