more error-prone issue fix

Change-Id: I49f2cc0459cfddddc6a99e2ebb8ad52d547e2909
diff --git a/apps/evpn-route-service/app/src/main/java/org/onosproject/evpnrouteservice/impl/EvpnRouteManager.java b/apps/evpn-route-service/app/src/main/java/org/onosproject/evpnrouteservice/impl/EvpnRouteManager.java
index 19e6311..28abb7d 100644
--- a/apps/evpn-route-service/app/src/main/java/org/onosproject/evpnrouteservice/impl/EvpnRouteManager.java
+++ b/apps/evpn-route-service/app/src/main/java/org/onosproject/evpnrouteservice/impl/EvpnRouteManager.java
@@ -81,7 +81,9 @@
     @Deactivate
     protected void deactivate() {
         evpnRouteStore.unsetDelegate(evpnRouteStoreDelegate);
-        listeners.values().forEach(EvpnListenerQueue::stop);
+        synchronized (this) {
+            listeners.values().forEach(EvpnListenerQueue::stop);
+        }
     }
 
     /**
@@ -148,6 +150,7 @@
     }
 
 
+    @Override
     public Collection<EvpnRouteTableId> getRouteTables() {
         return evpnRouteStore.getRouteTables();
     }