docs: private Map<Integer, Integer> getNodeIdToZonePrimaryCount(Cluster cluster,
                                                                StoreRoutingPlan storeRoutingPlan) {
          Map<Integer, Integer> nodeIdToZonePrimaryCount = Maps.newHashMap();
          for(Integer nodeId: cluster.getNodeIds()) {
              nodeIdToZonePrimaryCount.put(nodeId,
                                           storeRoutingPlan.getZonePrimaryPartitionIds(nodeId).size());
          }
  
          return nodeIdToZonePrimaryCount;
      }