public DynamicThrottlePolicy setWindowSizeBackOff(double windowSizeBackOff) {
        this.windowSizeBackOff = Math.max(0, Math.min(1, windowSizeBackOff));
        return this;
    }
Sets the factor of window size to back off to when the algorithm determines that efficiency is not increasing.
Capped to [0, 1]

@param windowSizeBackOff the back off to set
@return this, to allow chaining
messagebus/src/main/java/com/yahoo/messagebus/DynamicThrottlePolicy.java