Unable to register multiple instances of the same `Binder` class

[fabriziocucci]

Description

While writing the test case for #3675, I've noticed that it doesn't seem to be possible to register two instances of the same Binder class (either Jersey binder or HK2 binder).

Technically, the main cause seems to be in ComponentBag#registerModel:

private boolean registerModel(final Class<?> componentClass,
        final int defaultPriority,
        final Map<Class<?>, Integer> contractMap,
        final Inflector<ContractProvider.Builder, ContractProvider> modelEnhancer) {

    return Errors.process(() -> {
        if (models.containsKey(componentClass)) { // <-- true for the second binder!
                Errors.error(LocalizationMessages.COMPONENT_TYPE_ALREADY_REGISTERED(componentClass), Severity.HINT);
            return false;
        }
        ...
        });
}

Is this by design?

Test

• https://github.com/fabriziocucci/jersey-issue-3686

[kinow]

I'm facing an issue and thought it could be related to this one. But while debugging 2.26, I've found that the class was actually the implementation class, not the interface. I have a few implementations that use Feature. But the models.containsKey is correctly checking for the implementation value, not the interface name. Just my 0.02 cents.

[fabriziocucci]

But the models.containsKey is correctly checking for the implementation value, not the interface name.

@kinow that's exactly my point and it fails in the (corner) case where you register two instances of the same concrete class implementing the Binder interface (see example).

The only real (corner) case where I see this happening is if you have a concrete MyBinder class which accepts a generic command (e.g. Consumer<Binder>) performing some common bindings in the configure method before/after executing the instance-specific command.

I'm wondering whether returning true instead of false in the code snippet of the description wouldn't be enough to cover this...

[kinow]

Oh, sorry, thought you were referring to the interface.