Tighten precontinoal checks

Change-Id: If2bca48023d26655398e35f7e917bb617ce57963
diff --git a/core/api/src/main/java/org/onosproject/net/intent/IntentData.java b/core/api/src/main/java/org/onosproject/net/intent/IntentData.java
index e24e14e..c3277bc 100644
--- a/core/api/src/main/java/org/onosproject/net/intent/IntentData.java
+++ b/core/api/src/main/java/org/onosproject/net/intent/IntentData.java
@@ -58,6 +58,9 @@
      * @param version version of the intent for this key
      */
     public IntentData(Intent intent, IntentState state, Timestamp version) {
+        checkNotNull(intent);
+        checkNotNull(state);
+
         this.intent = intent;
         this.state = state;
         this.request = state;