private double calculateFeUsageCost(QuotaName quotaName, double usageCost) {
    return quotaName == QuotaName.READ_CAPACITY_UNIT ? usageCost * feReadUsageAmplificationFactor
        : usageCost * feWriteUsageAmplificationFactor;
  }
Calculate the amplified frontend usage cost to serve the usageCost for a {@link QuotaResource}.
Frontend usage cost could get amplified because to serve one copy of data, frontend might need to simultaneously
read or write the data over network to multiple storage nodes. The amplification factor is determined by the configs
defined in {@link RouterConfig}.
@param quotaName {@link QuotaName} object.
@param usageCost the usage cost for {@link QuotaResource}.
@return amplified frontend usage cost.
ambry-quota/src/main/java/com/github/ambry/quota/capacityunit/AmbryCUQuotaSource.java