ONOS-5309 Clearing installables from intent data object on successful uninstallation

Change-Id: Ic77af12f98bc1519efb2e2703223e340aa5b20e4
(cherry picked from commit 24389970b336c3bb2fb883f2aaa87f7b457bde4a)
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 84acfc3..feada17 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
@@ -114,7 +114,8 @@
     public IntentData(IntentData original, List<Intent> installables) {
         this(original);
 
-        this.installables = ImmutableList.copyOf(checkNotNull(installables));
+        this.installables = checkNotNull(installables).isEmpty() ?
+                Collections.emptyList() : ImmutableList.copyOf(installables);
     }
 
     // kryo constructor