This method should not be calling the getter of the directory/group because it performs a call to the server every time it is requested. Instead, I think this method should be substituted with:
```ruby
has_one :account_store [resource_class] # the [resource_class] part support might need to be added to the 'resource_prop_reader' method of the Associations module.
```
This method doesn't call the server every time it is requested; it loads the resource instance with what is returned from the previous call to get the account store mapping.

Please note that this will probably require modifications to the 'resource_prop_reader' method of the Associations module to support the 'resource_class' parameter.