@Override
    protected boolean prepareIntervals(int dataRef) {
        currentIntervals = store.get(dataRef);
        currentIntervalIndex = 1;
        currentInterval = currentIntervals[0];
        return true;
    }
Implementation of PostingList for regular features that store
their intervals and nothing else.

@author Magnar Nedland
@author bjorncs
predicate-search/src/main/java/com/yahoo/search/predicate/index/IntervalPostingList.java