private void nextStop() {
        if (stopsIterator.hasNext() == false) {
            alignment = null;
            return;
        }
        
        duration = minDuration;
        alignment = stopsIterator.next();

        // find interval, where is end in
        currentIntervalOfEnd = alignment.startValuesIndex;
        while (currentIntervalOfEnd < elementaryIntervals.size() &&
                elementaryIntervals.get(currentIntervalOfEnd).getEnd() <= alignment.startPoint + duration) { currentIntervalOfEnd++; }
    }