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

Change-Id: Ic77af12f98bc1519efb2e2703223e340aa5b20e4
(cherry picked from commit 24389970)

@@ -114,7 +114,8 @@ public class IntentData { //FIXME need to make this "immutable"
     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

@@ -36,6 +36,7 @@ import org.slf4j.Logger;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
@@ -112,7 +113,8 @@ class IntentInstaller {
                         uninstallData.setState(WITHDRAWN);
                         break;
                 }
-                store.write(uninstallData);
+                // Intent has been withdrawn; we can clear the installables
+                store.write(new IntentData(uninstallData, Collections.emptyList()));
             }
         };