private void addAccount(DataSeries item, Account account, List<Exception> warnings) {
    PerformanceIndex accountIndex = dataCache.get(account);

    if (accountIndex == null) {
      accountIndex =
          PerformanceIndex.forAccount(getClient(), account, getReportingPeriod(), warnings);
      dataCache.put(account, accountIndex);
    }

    addScatterSeries(item, accountIndex);
  }