OperationStepHandlers may wish to determine service names for capability-provided services regardless of whether the capabilities are actually installed. A common case of this is when the dependent service is Mode.PASSIVE – the installing OSH wants the service to come up if the dependency is ever satisfied, and it's not an error if the dependency is not satisfied right now. If the OperationContext will throw an exception right now when the OSH tries to learn the service name, then this kind of wiring can no longer be done.

I need to think some about how OSHs should record the capability relationship in this kind of situation. (Is it a form of runtime-only requirement?) But now that the OC knows how to create a service name regardless of whether the capability is registered, I see no reason to fail a getCapabilityServiceName call.