@Override
    public Collection<TrendBar> getBars(Symbol symbol, PeriodType periodType, long from, long to) {
        if (to < from) {
            throw new IllegalArgumentException("To can not be earlier from");
        }
        Collection<TrendBar> trendBars = trendBarDao.getTrendBars(symbol, periodType, from, to);
        return returnCollection(trendBars);
    }