When using InvocationHandlers representing many different objects it's very easy to make mistakes by creating an InvocationHandler for the wrong object, e.g. the method

class SupportLibServiceWorkerControllerAdapter:
   public InvocationHandler getServiceWorkerWebSettings()

should return an InvocationHandler representing ServiceWorkerWebSettingsBoundaryInterface, but we currently have no (compile-time) mechanism to ensure the returned InvocationHandler represents a ServiceWorkerWebSettingsBoundaryInterface.

You could for example implement getServiceWorkerWebSettings in the following way without compilation errors:


public InvocationHandler getServiceWorkerWebSettings() {
    return BoundaryInterfaceReflectionUtil.createInvocationHandlerFor(
            mAwServiceWorkerController.getAwServiceWorkerSettings()); // Wrong, this is an AwServiceWorkerSettings object, not a ServiceWorkerWebSettingsBoundaryInterface
}


One possibility here would be to have BoundaryInterfaceReflectionUtil.createInvocationHandlerFor return a new class implementing InvocationHandler:
TemplatedInvocationHandler<BoundaryInterface>
which declares a specific boundary interface as template, to ensure we type-check InvocationHandlers.
An alternative could be to use some kind of annotation for each invocationhandler.

Nate, WDYT?