Make the return type of Instance.handles() covariant #570
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The `Instance.handles()` method returns an `Iterable` of contextual reference handles (`Instance.Handle<T>`). It used to be defined in an invariant way (`Iterable<Handle<T>>`), which prevents CDI Lite implementations from exposing subtypes of `Instance` and `Instance.Handle` as public API. This commit changes the return type to covariant `Iterable<? extends Handle<T>>`. With that change, CDI Lite implementations can expose a `CustomInstance`, which extends `Instance` and overrides the `Instance.handles()` method. The method, in turn, can return `Iterable<CustomInstanceHandle<T>>`, where `CustomInstanceHandle` extends `Instance.Handle`.
graemerocher
approved these changes
Dec 1, 2021
manovotn
approved these changes
Dec 1, 2021
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The
Instance.handles()method returns anIterableof contextualreference handles (
Instance.Handle<T>). It used to be defined inan invariant way (
Iterable<Handle<T>>), which prevents CDI Liteimplementations from exposing subtypes of
InstanceandInstance.Handleas public API. This commit changes the returntype to covariant
Iterable<? extends Handle<T>>. With that change,CDI Lite implementations can expose a
CustomInstance, which extendsInstanceand overrides theInstance.handles()method. The method,in turn, can return
Iterable<CustomInstanceHandle<T>>, whereCustomInstanceHandleextendsInstance.Handle.