private long calculateErrorTimeout() {
        return timingValues.getPlusMinusFractionRandom(timingValues.getErrorTimeout(), randomFraction);
    }
Requests the config for the {@link com.yahoo.config.ConfigInstance} on the given {@link ConfigSubscription}

@param sub a subscription
config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigRequester.java