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/types/LispSourceDestLcafAddress.java b/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/types/LispSourceDestLcafAddress.java
index 80dd538..954c2b4 100644
--- a/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/types/LispSourceDestLcafAddress.java
+++ b/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/types/LispSourceDestLcafAddress.java
@@ -23,6 +23,7 @@
 import java.util.Objects;
 
 import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
  * Source/Dest key type LCAF address class.
@@ -248,6 +249,10 @@
          * @return LispSourceDestLcafAddress instance
          */
         public LispSourceDestLcafAddress build() {
+
+            checkNotNull(srcPrefix, "Must specify a source address prefix");
+            checkNotNull(dstPrefix, "Must specify a destination address prefix");
+
             return new LispSourceDestLcafAddress(reserved1, reserved2, flag, length,
                     reserved, srcMaskLength, dstMaskLength, srcPrefix, dstPrefix);
         }