Use Long.hashCode(long) to avoid manual hash code calculation

Change-Id: I5f4aa8b80339a0c671ff2d12f8ba25dba023f220
diff --git a/core/api/src/main/java/org/onosproject/net/IndexedLambda.java b/core/api/src/main/java/org/onosproject/net/IndexedLambda.java
index 5a0077b..cb7e1ae 100644
--- a/core/api/src/main/java/org/onosproject/net/IndexedLambda.java
+++ b/core/api/src/main/java/org/onosproject/net/IndexedLambda.java
@@ -44,7 +44,7 @@
 
     @Override
     public int hashCode() {
-        return (int) (index ^ (index >>> 32));
+        return Long.hashCode(index);
     }
 
     @Override