public long getPlusMinusFractionRandom(long value, float fraction) {
        return Math.round(value - (value * fraction) + (rand.nextFloat() * 2L * value * fraction));
    }
Returns a number +/- a random component

@param value      input
@param fraction for instance 0.1 for +/- 10%
@return a number
config/src/main/java/com/yahoo/vespa/config/TimingValues.java