code: function (items) {
          var self = this;
  
          self.items().add(self.create(items)).parent(self);
  
          return self;
        }
docs: Adds one or many items to the current container. This will create instances of
  the object representations if needed.
  
  @method add
  @param {Array/Object/tinymce.ui.Control} items Array or item that will be added to the container.
  @return {tinymce.ui.Collection} Current collection control.