Override @c Subscriber Default Endpoint

 namespace pubsub = ::google::cloud::pubsub; using ::google::cloud::Options; [](std::string project_id, std::string subscription_id) { auto subscription = pubsub::Subscription(std::move(project_id), std::move(subscription_id)); return pubsub::Subscriber(pubsub::MakeSubscriberConnection( std::move(subscription), Options{}.set<google::cloud::EndpointOption>( "private.googleapis.com"))); }