docs: @Override
      public ImmutableMap<Integer, Long> pointInTimeCache() {
          if (m_shutdown.get()) {
              throw new RuntimeException("Requested cache from shutdown LeaderCache.");
          }
          HashMap<Integer, Long> cacheCopy = new HashMap<Integer, Long>();
          for (Entry<Integer, LeaderCallBackInfo> e : m_publicCache.entrySet()) {
              cacheCopy.put(e.getKey(), e.getValue().m_HSId);
          }
          return ImmutableMap.copyOf(cacheCopy);
      }