private void mergeIntervals(Set<Interval> intervals) {
        for (Interval a : intervals) {
            for (Interval b : intervals) {
                if (a.abuts(b)) {
                    if (a.isBefore(b)) {
                        assert a.getEnd().equals(b.getStart());
                        intervals.add(new Interval(a.getStart(), b.getEnd()));
                    } else {
                        assert b.getEnd().equals(a.getStart());
                        intervals.add(new Interval(b.getStart(), a.getEnd()));
                    }

                    intervals.remove(a);
                    intervals.remove(b);
                }
            }
        }
    }