Add REST interface for configuring ARP mode

Change-Id: Ib2b6edb133879054d235dbd4762ba95e1e03793c
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/util/OpenstackNetworkingUtil.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/util/OpenstackNetworkingUtil.java
index 2d8bd12..609b580 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/util/OpenstackNetworkingUtil.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/util/OpenstackNetworkingUtil.java
@@ -60,6 +60,7 @@
 import java.util.TreeMap;
 
 import static com.fasterxml.jackson.databind.SerializationFeature.INDENT_OUTPUT;
+import static com.google.common.base.Strings.isNullOrEmpty;
 import static org.onosproject.openstacknetworking.api.Constants.PCISLOT;
 import static org.onosproject.openstacknetworking.api.Constants.PCI_VENDOR_INFO;
 import static org.onosproject.openstacknetworking.api.Constants.portNamePrefixMap;
@@ -84,6 +85,9 @@
     private static final String IDENTITY_PATH = "identity/";
     private static final String SSL_TYPE = "SSL";
 
+    private static final String PROXY_MODE = "proxy";
+    private static final String BROADCAST_MODE = "broadcast";
+
     private static final String ERR_FLOW = "Failed set flows for floating IP %s: ";
 
     /**
@@ -364,6 +368,21 @@
     }
 
     /**
+     * Checks the validity of ARP mode.
+     *
+     * @param arpMode ARP mode
+     * @return returns true if the ARP mode is valid, false otherwise
+     */
+    public static boolean checkArpMode(String arpMode) {
+
+        if (isNullOrEmpty(arpMode)) {
+            return false;
+        } else {
+            return arpMode.equals(PROXY_MODE) || arpMode.equals(BROADCAST_MODE);
+        }
+    }
+
+    /**
      * Builds up and a complete endpoint URL from gateway node.
      *
      * @param node gateway node