When a bean with a field @RootContext Activity activity is injected in another bean with the singleton scope, the field is null, because by design singleton doesn't store ref to activities, in order to avoid memory leaks.

Having an activity field null leads to hard to find bugs, especially for AA beginners.

I think AA should prevent such case, by throwing an exception like IllegalStateException. If the user want to inject the activity in @RootContext, there must be a good reason for that, and so we must warn him he can't do that if the bean is injected in a signleton bean.

WDYT?