code: function (key) {
                  var map = this._getMap(key, false);
                  if (map == null) {
                      return false;
                  }
                  var item;
                  if (map == this._objectKeys) {
                      item = key[this._metaDataName];
                  } else if (map != this._otherKeys) {
                      item = map[key];
                  } else {
                      for (var i in map) {
                          if (map.hasOwnProperty(i)) {
                              var elt = map[i];
                              if (key === elt.key) {
                                  item = elt;
                                  break;
                              }
                          }
                      }
                  }
                  if (item) {
                      return true;
                  } else {
                      return false;
                  }
              }
docs: Checks if a key is in the StackHashMap object and returns true if it is found.
  @param {MultiTypes} key key which was used to add the entry in the StackHashMap object.
  @return {Boolean} True if there is an entry that was added with the same key.