code: public Iterator<String> getSpaces() {
          log.debug("getSpaces()");
  
          List<String> spaces = new ArrayList<>();
          List<Bucket> buckets = listAllBuckets();
          for (Bucket bucket : buckets) {
              String bucketName = bucket.getName();
              if (isSpace(bucketName)) {
                  spaces.add(getSpaceId(bucketName));
              }
          }
  
          // sort after the bucket prefix has been stripped off
          Collections.sort(spaces);
  
          return spaces.iterator();
      }
docs: {@inheritDoc}