code: @SuppressWarnings("unchecked")
      private Object injectMap(Object obj, int i) {
          Map<String, Object> map;
          String key = keys[i];
          if (obj == null) {
              map = new LinkedHashMap<String, Object>();
          } else {
              map = (Map<String, Object>) obj;
          }
  
          if (model == Model.add) {
              if (i == keys.length - 1) {
                  map.put(key, val);
                  return map;
              }
              if (!map.containsKey(key) || map.get(key) == null) {
                  map.put(key, inject(null, i + 1));
                  return map;
              }
          } else if (model == Model.del) {
              if (i == keys.length - 1) {
                  map.remove(key);
                  return map;
              }
              if (!map.containsKey(key) || map.get(key) == null) {
                  return map;
              }
          } else if (model == Model.cell) {
              if (i == keys.length - 1) {
                  cellObj = map.get(key);
                  return map;
              }
              if (!map.containsKey(key) || map.get(key) == null) {
                  return map;
              }
          }
  
          if (map.containsKey(key) && map.get(key) != null) {
              inject(map.get(key), i + 1);
          }
          return map;
      }
docs: 注入MAP
  
  @param obj
  @param i