docs: public Set<String> getUnclaimed() {
          synchronized (cluster.allWorkUnits) {
              LinkedHashSet<String> result = new LinkedHashSet<String>(cluster.allWorkUnits.keySet());
              result.removeAll(cluster.workUnitMap.keySet());
              result.addAll(cluster.getHandoffWorkUnits());
              result.removeAll(cluster.getHandoffResultWorkUnits());
              result.removeAll(cluster.myWorkUnits);
              return result;
          }
      }