Need to do more testing and write a test but it looks like if I have an InjectionResolver and restrict its visibility to local it will still be used by descendant ServiceLocators.

The SingletonContext contains a locatorID check that prevents it from destroying Singleton Services injected into child ServiceLocators. This means that when the SingletonContext is shutdown it will not destroy Singleton services that were created and injected into a child ServiceLocator. This leads to resource leaks and strange behavior unless the parent ServiceLocator is careful to inject every Singleton service.

Instead, when the SingletonContext is shutdown it should destroy any Singleton service that was provided to the current ServiceLocator or to a descendant ServiceLocator.

In HK2 it is possible to retrieve the parent of a ServiceLocator using the ServiceLocator.getParent method. There is no way to retrieve the children of a ServiceLocator. There should be a way to retrieve all the children of the ServiceLocator. A public method:

Set<ServiceLocator> getChildren();

should be added to the ServiceLocator interface and implemented.