code: public void insert(long time, long count) throws IllegalArgumentException {
      if (count < 0) {
        throw new IllegalArgumentException("negative count");
      } else if (count > 0) {
        if (time == MIN_VALUE) {
          //MIN_VALUE means a box is unused so we avoid it
          time++;
        }
        merge(makeBoxes(time, count), count);
      }
    }
docs: Bulk insert {@code count} events at {@code time}.
  
  @param time event time
  @param count event count
  @throws IllegalArgumentException if count is negative