Fix: resolve the service not found exception caused by openstack4j

Change-Id: I33a5c7e6b91758a61662a77a1b347fd0239219eb
diff --git a/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/OpenstackNetworkService.java b/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/OpenstackNetworkService.java
index 7b192f1..d0bab0f 100644
--- a/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/OpenstackNetworkService.java
+++ b/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/OpenstackNetworkService.java
@@ -16,6 +16,7 @@
 package org.onosproject.openstacknetworking.api;
 
 import org.onlab.packet.IpAddress;
+import org.onlab.packet.IpPrefix;
 import org.onlab.packet.MacAddress;
 import org.onosproject.event.ListenerService;
 import org.openstack4j.model.network.ExternalGateway;
@@ -100,6 +101,14 @@
     Set<Port> ports(String networkId);
 
     /**
+     * Obtains a set of fixed IP addresses managed by the given network type.
+     *
+     * @param type network type (FLAT, VXLAN, VLAN, etc.)
+     * @return a set of fixed IP addresses
+     */
+    Set<IpPrefix> getFixedIpsByNetworkType(String type);
+
+    /**
      * Returns external router mac with supplied external gateway.
      *
      * @param externalGateway external gateway information