Reverting changes aim to return the immutable copy during cloning.
- Copy builder is expected to return the mutable copy of ResourceId builder.

Change-Id: Ie66d7679c1977cb8d287b80d45b41f5f29ea54b8
diff --git a/model/src/main/java/org/onosproject/yang/model/ListKey.java b/model/src/main/java/org/onosproject/yang/model/ListKey.java
index 9f643a4..576a21c 100644
--- a/model/src/main/java/org/onosproject/yang/model/ListKey.java
+++ b/model/src/main/java/org/onosproject/yang/model/ListKey.java
@@ -64,11 +64,11 @@
     @Override
     public ListKey clone() throws CloneNotSupportedException {
         ListKey clonedListKey = (ListKey) super.clone();
-        ImmutableList.Builder<KeyLeaf> clonedKeyLeafs = ImmutableList.builder();
+        List<KeyLeaf> clonedKeyLeafs = new LinkedList<>();
         for (KeyLeaf leaf : keyLeafs) {
             clonedKeyLeafs.add(leaf.clone());
         }
-        clonedListKey.keyLeafs = clonedKeyLeafs.build();
+        clonedListKey.keyLeafs = clonedKeyLeafs;
         return clonedListKey;
     }