Initial support GRE tunnel at SONA

Change-Id: I86536a3ed23d8df45e1dc4033c3068a4dfc9ec73
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackNetworkManager.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackNetworkManager.java
index d08ea96..e7cda54 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackNetworkManager.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackNetworkManager.java
@@ -396,6 +396,11 @@
                         .filter(n -> n.getNetworkType() == NetworkType.VXLAN)
                         .map(IdEntity::getId).collect(Collectors.toSet());
                 break;
+            case "GRE" :
+                networkIds = networks.stream()
+                        .filter(n -> n.getNetworkType() == NetworkType.GRE)
+                        .map(IdEntity::getId).collect(Collectors.toSet());
+                break;
             case "VLAN" :
                 networkIds = networks.stream()
                         .filter(n -> n.getNetworkType() == NetworkType.VLAN)