Fixed to not to create gateway group if it is already exists

Also changed some names shorter.

Change-Id: Iaa8aa5ac378fc168e79c9e238090ca817af42261
diff --git a/apps/openstacknetworking/routing/src/main/java/org/onosproject/openstacknetworking/routing/OpenstackRoutingRulePopulator.java b/apps/openstacknetworking/routing/src/main/java/org/onosproject/openstacknetworking/routing/OpenstackRoutingRulePopulator.java
index d2c928f..875cf98 100644
--- a/apps/openstacknetworking/routing/src/main/java/org/onosproject/openstacknetworking/routing/OpenstackRoutingRulePopulator.java
+++ b/apps/openstacknetworking/routing/src/main/java/org/onosproject/openstacknetworking/routing/OpenstackRoutingRulePopulator.java
@@ -188,7 +188,7 @@
 
         tBuilder.setIpSrc(externalIp);
         gatewayService.getGatewayNodes().forEach(node -> {
-            tBuilder.setOutput(gatewayService.getGatewayExternalPort(node.getGatewayDeviceId()));
+            tBuilder.setOutput(gatewayService.getUplinkPort(node.getGatewayDeviceId()));
             ForwardingObjective fo = DefaultForwardingObjective.builder()
                     .withSelector(sBuilder.build())
                     .withTreatment(tBuilder.build())
@@ -380,7 +380,7 @@
         StreamSupport.stream(deviceService.getDevices().spliterator(), false)
                 .filter(d -> isTypeOf(d.id(), OpenstackNodeService.NodeType.COMPUTE))
                 .forEach(d -> populateRuleToGatewayBySgw(d.id(),
-                        gatewayService.getGroupIdForGatewayLoadBalance(d.id()), vni));
+                        gatewayService.getGatewayGroupId(d.id()), vni));
     }
 
     private void populateRuleToGatewayBySgw(DeviceId deviceId, GroupId groupId, long vni) {
@@ -548,7 +548,7 @@
     }
 
     private PortNumber getExternalPortNum(DeviceId deviceId) {
-        return checkNotNull(gatewayService.getGatewayExternalPort(deviceId), PORTNOTNULL);
+        return checkNotNull(gatewayService.getUplinkPort(deviceId), PORTNOTNULL);
     }
 
     /**