add get pivot class method

Author: taylorotwell

src/Illuminate/Database/Eloquent/Relations/BelongsToMany.php

@@ -6,6 +6,7 @@
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Collection;
+use Illuminate\Database\Eloquent\Relations\Pivot;
 use Illuminate\Database\Eloquent\ModelNotFoundException;
 
 class BelongsToMany extends Relation
@@ -266,6 +267,16 @@ protected function buildDictionary(Collection $results)
         return $dictionary;
     }
 
+    /**
+     * Get the class being used for pivot models.
+     *
+     * @return string
+     */
+    public function getPivotClass()
+    {
+        return $this->using ?? Pivot::class;
+    }
+
     /**
      * Specify the custom pivot model to use for the relationship.
      *