[ONOS-3188] Add the method: Returns the virtualPort associated with the
fixedIP.

Change-Id: I4f66287a4186cc103070c9182dae64f81fcd6488
diff --git a/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/virtualport/impl/VirtualPortManager.java b/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/virtualport/impl/VirtualPortManager.java
index 926809c..c45373b 100644
--- a/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/virtualport/impl/VirtualPortManager.java
+++ b/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/virtualport/impl/VirtualPortManager.java
@@ -17,9 +17,12 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
@@ -68,6 +71,7 @@
     private static final String TENANTID_NOT_NULL = "TenantId  cannot be null";
     private static final String NETWORKID_NOT_NULL = "NetworkId  cannot be null";
     private static final String DEVICEID_NOT_NULL = "DeviceId  cannot be null";
+    private static final String FIXEDIP_NOT_NULL = "FixedIp  cannot be null";
 
     protected Map<VirtualPortId, VirtualPort> vPortStore;
     protected ApplicationId appId;
@@ -125,6 +129,25 @@
     }
 
     @Override
+    public VirtualPort getPort(FixedIp fixedIP) {
+        checkNotNull(fixedIP, FIXEDIP_NOT_NULL);
+        List<VirtualPort> vPorts = new ArrayList<>();
+        vPortStore.values().stream().forEach(p -> {
+            Iterator<FixedIp> fixedIps = p.fixedIps().iterator();
+            while (fixedIps.hasNext()) {
+                if (fixedIps.next().equals(fixedIP)) {
+                    vPorts.add(p);
+                    break;
+                }
+            }
+        });
+        if (vPorts.size() == 0) {
+            return null;
+        }
+        return vPorts.get(0);
+    }
+
+    @Override
     public Collection<VirtualPort> getPorts() {
         return Collections.unmodifiableCollection(vPortStore.values());
     }