Give bills groups too.

app/Models/Bill.php

@@ -161,6 +161,14 @@ class Bill extends Model
         return $this->morphMany(Note::class, 'noteable');
     }
 
+    /**
+     * Get all of the tags for the post.
+     */
+    public function objectGroups()
+    {
+        return $this->morphToMany(ObjectGroup::class, 'object_groupable');
+    }
+
     /**
      * @codeCoverageIgnore
      *