code: @SuppressWarnings("unchecked")
      public RoutingStrategy getRoutingStrategy(String storeName) {
          // acquire read lock
          readLock.lock();
          try {
              Map<String, RoutingStrategy> routingStrategyMap = (Map<String, RoutingStrategy>) metadataCache.get(ROUTING_STRATEGY_KEY)
                                                                                                            .getValue();
              RoutingStrategy strategy = routingStrategyMap.get(storeName);
              if(strategy == null) {
                  Map<String, RoutingStrategy> systemRoutingStrategyMap = (Map<String, RoutingStrategy>) metadataCache.get(SYSTEM_ROUTING_STRATEGY_KEY)
                                                                                                                      .getValue();
                  strategy = systemRoutingStrategyMap.get(storeName);
              }
              return strategy;
          } finally {
              readLock.unlock();
          }
      }
docs: /*
  First check in the map of regular stores. If not present, check in the
  system stores map.