code: public void wipeZeros() {
          Set<T> objToBeRemoved = new HashSet<T>();
          for (T obj : objToCounts.keySet()) {
              if (shouldBeRemovedFromCounter(obj)) {
                  objToBeRemoved.add(obj);
              }
          }
          for (T obj : objToBeRemoved) {
              objToCounts.remove(obj);
          }
      }
docs: Remove any object from the counter whose total count is zero (to free up
  memory).