code: private static void removeEmptyTicks(List<Tick> ticks) {
          for (int i = ticks.size() - 1; i >= 0; i--) {
              if (ticks.get(i).getTrades() == 0) {
                  ticks.remove(i);
              }
          }
      }
docs: Removes all empty (i.e. with no trade) ticks of the list.
  @param ticks a list of ticks