如何修改Select2 AllowClear函数？

Question

我为 Select2 Selection 创建了一个自定义适配器，我想在其中直接在选择而不是下拉列表中显示输入字段。

$.fn.select2.amd.define('SearchableSingleSelection', [
  'select2/utils',
  'select2/selection/single',
  'select2/selection/eventRelay',
  'select2/dropdown/search'
], function(Utils, SingleSelection, EventRelay, DropdownSearch) {
  var adapter = Utils.Decorate(SingleSelection, DropdownSearch);
  adapter = Utils.Decorate(adapter, EventRelay);

  /**
   * Renders the custom Select2 element with a search field inside.
   * @returns {jQuery} The rendered Select2 element.
   */
  adapter.prototype.render = function() {
    var $rendered = DropdownSearch.prototype.render.call(this, SingleSelection.prototype.render);
    this.$searchContainer.hide();
    if (this.options.options.minimumResultsForSearch === Infinity) {
      this.$searchContainer.find('input').prop("disabled", "disabled");
    }
    if (this.options.options.maximumInputLength) {
      this.$searchContainer.find('input').attr("maxlength", this.options.options.maximumInputLength);
    }
    this.$element.siblings('.select2').find('.selection').prepend(this.$searchContainer);
    return $rendered;
  };

  var bindOrigin = adapter.prototype.bind;
  adapter.prototype.bind = function(container) {
    var self = this;
    bindOrigin.apply(this, arguments);
    container.on('open', function() {
      self.$selection.hide();
      self.$searchContainer.show();
      self.$searchContainer.find('input')[0].focus();
    });
    container.on('close', function() {
      self.$searchContainer.hide();
      self.$selection.show();
      self.$searchContainer.find('input')[0].blur();
    });
  };

  return adapter;
});

现在我也想自定义 AllowClear 功能，因为它不起作用。如何修改 AllowClear.prototype.update 和 AllowClear.prototype._handleClear 函数？