Various small fixes

Change-Id: I83802169d0d968f7b88d4be2cedba74b15fdd7da
diff --git a/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/RouterGateway.java b/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/RouterGateway.java
index 27e1473..6aef24e 100644
--- a/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/RouterGateway.java
+++ b/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/RouterGateway.java
@@ -35,7 +35,7 @@
     private RouterGateway(TenantNetworkId networkId, boolean enableSnat,
                          Set<FixedIp> externalFixedIps) {
         this.networkId = checkNotNull(networkId, "networkId cannot be null");
-        this.enableSnat = checkNotNull(enableSnat, "enableSnat cannot be null");
+        this.enableSnat = enableSnat;
         this.externalFixedIps = checkNotNull(externalFixedIps, "externalFixedIps cannot be null");
     }