Fix duplicate host event

Change-Id: I632a1482e7b1b768ce7a0243cc8b6b398b9825b7
diff --git a/core/net/src/main/java/org/onosproject/net/host/impl/HostManager.java b/core/net/src/main/java/org/onosproject/net/host/impl/HostManager.java
index 1473f33..f48b836 100644
--- a/core/net/src/main/java/org/onosproject/net/host/impl/HostManager.java
+++ b/core/net/src/main/java/org/onosproject/net/host/impl/HostManager.java
@@ -192,10 +192,7 @@
     @Override
     public void removeHost(HostId hostId) {
         checkNotNull(hostId, HOST_ID_NULL);
-        HostEvent event = store.removeHost(hostId);
-        if (event != null) {
-            post(event);
-        }
+        store.removeHost(hostId);
     }
 
     // Personalized host provider service issued to the supplied provider.
@@ -211,11 +208,8 @@
             checkNotNull(hostId, HOST_ID_NULL);
             checkValidity();
             hostDescription = validateHost(hostDescription, hostId);
-            HostEvent event = store.createOrUpdateHost(provider().id(), hostId,
+            store.createOrUpdateHost(provider().id(), hostId,
                                                        hostDescription, replaceIps);
-            if (event != null) {
-                post(event);
-            }
         }
 
         // returns a HostDescription made from the union of the BasicHostConfig
@@ -231,20 +225,14 @@
         public void hostVanished(HostId hostId) {
             checkNotNull(hostId, HOST_ID_NULL);
             checkValidity();
-            HostEvent event = store.removeHost(hostId);
-            if (event != null) {
-                post(event);
-            }
+            store.removeHost(hostId);
         }
 
         @Override
         public void removeIpFromHost(HostId hostId, IpAddress ipAddress) {
             checkNotNull(hostId, HOST_ID_NULL);
             checkValidity();
-            HostEvent event = store.removeIp(hostId, ipAddress);
-            if (event != null) {
-                post(event);
-            }
+            store.removeIp(hostId, ipAddress);
         }
     }