The line you quote is an initializer for plugins managed by the plugin manager that are "ServiceLocatorAware". It does not indicate that there are any such trees _in_ _the_ _framework_, which is what I wanted to see if you can demonstrate. I'm still not seeing any evidence of that. (The FormElementManager does not create other plugin managers, but instead composes them.)

If you are in a situation where you have a tree of plugin managers, you can get to the top one by performing a do/while loop:

```php
do {
    $services = $services->getServiceLocator();
} while ($services instanceof AbstractPluginManager);
```