Aligned to new `EventSender` interface

event-listener-provider/src/main/java/org/gcube/keycloak/event/NoOpEventPublisherProvider.java

@@ -1,6 +1,7 @@
 package org.gcube.keycloak.event;
 
 import org.gcube.event.publisher.EventSender;
+import org.json.simple.JSONObject;
 import org.keycloak.events.Event;
 import org.keycloak.events.admin.AdminEvent;
 
@@ -38,6 +39,18 @@ public class NoOpEventPublisherProvider extends OrchestratorEventPublisherProvid
             public void send(org.gcube.event.publisher.Event event) {
                 // Nothing to do
             }
+
+            @Override
+            public String sendAndGetResult(org.gcube.event.publisher.Event event) {
+                // Nothing to do
+                return null;
+            }
+
+            @Override
+            public JSONObject retrive(String id) {
+                // Nothing to do
+                return null;
+            }
         };
     }