Add NotNull and Argument check during object build for LISP object

Also correct IP enumeration type into IP4.

Change-Id: Id970ee608c885826cfd2de7b5448b2bc451e079f
diff --git a/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/protocols/DefaultLispLocatorRecord.java b/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/protocols/DefaultLispLocatorRecord.java
index 37eeb71..0b5407e 100644
--- a/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/protocols/DefaultLispLocatorRecord.java
+++ b/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/protocols/DefaultLispLocatorRecord.java
@@ -24,6 +24,7 @@
 import org.onosproject.lisp.msg.types.LispAfiAddress;
 
 import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkNotNull;
 import static org.onosproject.lisp.msg.types.LispAfiAddress.AfiAddressWriter;
 
 /**
@@ -209,6 +210,9 @@
 
         @Override
         public LispLocatorRecord build() {
+
+            checkNotNull(locatorAfi, "Must specify a locator address");
+
             return new DefaultLispLocatorRecord(priority, weight, multicastPriority,
                     multicastWeight, localLocator, rlocProbed, routed, locatorAfi);
         }