update the return statement inside the body of the isEmpty() method

Author: D-Coder135

Diff for: src/stack/usingLinkedList/implementation/LinkedListStack.java

@@ -116,6 +116,6 @@ public E pop() {
      */
     @Override
     public boolean isEmpty() {
-        return false;
+        return topOfStackRef == null;
     }
 }