code: @Override
      public CompletableFuture<Integer> getNumberOfOngoingTransactions() {
          return store.getChildren(activeTxRoot).thenCompose(list ->
                  Futures.allOfWithResults(list.stream().map(epoch ->
                          getNumberOfOngoingTransactions(Integer.parseInt(epoch))).collect(Collectors.toList())))
                      .thenApply(list -> list.stream().reduce(0, Integer::sum));
      }
docs: region overrides