Map<QuotaResource, LinkedList<RequestInfo>> getRequestQueue(QuotaMethod quotaMethod) {
    return quotaMethod == QuotaMethod.READ ? readRequestQueue : writeRequestQueue;
  }
@param quotaMethod {@link QuotaMethod} of the requested request queue.
@return the request queue of the OperationController corresponding to quotaMethod.
ambry-router/src/main/java/com/github/ambry/router/QuotaAwareOperationController.java