countMap.entrySet().iterator();

          @Override
          protected @Nullable Entry<E> computeNext() {
            while (true) {
              if (!mapEntries.hasNext()) {
                return endOfData();
              }
              Map.Entry<E, AtomicInteger> mapEntry = mapEntries.next();
              int count = mapEntry.getValue().get();
              if (count != 0) {