docs: @Override
      public Map<String, List<WorkerInfo>> getWorkerHostMap() {
          final List<WorkerInfo> workerInfos = getAllWorkers();
          final Map<String, List<WorkerInfo>> hostMap = new TreeMap<String, List<WorkerInfo>>();
          for (final WorkerInfo workerInfo : workerInfos) {
              List<WorkerInfo> hostWIs = hostMap.get(workerInfo.getHost());
              if (hostWIs == null) {
                  hostWIs = new ArrayList<WorkerInfo>();
                  hostMap.put(workerInfo.getHost(), hostWIs);
              }
              hostWIs.add(workerInfo);
          }
          return hostMap;
      }