private double scoreDelta(BrokerUpdater.Broker srcBrokerBefore, BrokerUpdater.Broker destBrokerBefore, BrokerUpdater.Broker srcBrokerAfter, BrokerUpdater.Broker destBrokerAfter) {
        double scoreBefore = Math.min(brokerScore(srcBrokerBefore), brokerScore(destBrokerBefore));
        double scoreAfter = Math.min(brokerScore(srcBrokerAfter), brokerScore(destBrokerAfter));
        return GoalUtils.linearNormalization(scoreAfter - scoreBefore, 1.0, -1.0);
    }
Calculate the score difference of src and dest. The score should be normalized to [0, 1.0]

@param srcBrokerBefore  source broker before action
@param destBrokerBefore dest broker before action
@param srcBrokerAfter   source broker after action
@param destBrokerAfter  dest broker after action
@return normalized score. < 0.5 means negative action
== 0.5 means action with no affection
> 0.5 means positive action
core/src/main/java/kafka/autobalancer/goals/AbstractGoal.java