code: private Map<String, String[]> getShards(DBCollection collection) {
          DB config = collection.getDB().getSisterDB("config");
          DBCollection configShards = config.getCollection("shards");
  
          DBCursor cursorShards = configShards.find();
  
          Map<String, String[]> map = new HashMap<>();
          while (cursorShards.hasNext()) {
              DBObject currentShard = cursorShards.next();
              String currentHost = (String) currentShard.get("host");
              int slashIndex = currentHost.indexOf("/");
              if (slashIndex > 0) {
                  map.put((String) currentShard.get(MONGO_DEFAULT_ID),
                          currentHost.substring(slashIndex + 1).split(","));
              }
          }
          return map;
      }
docs: Gets shards.
  
  @param collection the collection
  @return the shards