private QuotaUsageLevel computeWarningLevel(float usagePercentage) {
    if (usagePercentage >= 100) {
      return QuotaUsageLevel.EXCEEDED;
    }
    if (usagePercentage >= CRITICAL_USAGE_LEVEL_LIMIT) {
      return QuotaUsageLevel.CRITICAL;
    }
    if (usagePercentage >= healthyUsageLevelLimit) {
      return QuotaUsageLevel.WARNING;
    }
    return QuotaUsageLevel.HEALTHY;
  }
Compute the warning level from usage percentage.
@param usagePercentage usage of quota.
@return QuotaWarningLevel object.
ambry-quota/src/main/java/com/github/ambry/quota/SimpleQuotaRecommendationMergePolicy.java