@RequiresProxyRestart
    @Min(1)
    @JsonPropertyDescription("The number of threads to consume from the forward queue.")
    public int getForwardThreadCount() {
        return forwardThreadCount;
    }
If we fail to send, how much to increase the retryDelay duration by after each retry failure,
e.g. 1.1 means increase by 10% each time,
i.e. if retryDelay is 1000 and retryDelayGrowthFactor is 1.1, then the retry delays will be
1000, 1100, 1210, 1331, 1464, etc. Default value of 1 so the times don't increase.
stroom-proxy/stroom-proxy-app/src/main/java/stroom/proxy/app/handler/ForwardQueueConfig.java