Make the CartItem aware of its cart instance

src/Cart.php

@@ -813,6 +813,8 @@ class Cart
             $cartItem->setQuantity($qty);
         }
 
+        $cartItem->setInstance($this->instance);
+
         return $cartItem;
     }
 

src/CartItem.php

@@ -95,6 +95,13 @@ class CartItem implements Arrayable, Jsonable
      */
     private $discountRate = 0;
 
+    /**
+     * The cart instance of the cart item.
+     *
+     * @var string
+     */
+    public $instance;
+
     /**
      * CartItem constructor.
      *
@@ -372,6 +379,20 @@ class CartItem implements Arrayable, Jsonable
         return $this;
     }
 
+    /**
+     * Set cart instance
+     *
+     * @param string $instance
+     *
+     * @return \Gloudemans\Shoppingcart\CartItem
+     */
+    public function setInstance($instance)
+    {
+        $this->instance = $instance;
+
+        return $this;
+    }
+
     /**
      * Get an attribute from the cart item or get the associated model.
      *