How extend select2 adaptor with options checking? - jquery-select2

Question

I want to extend select2 default dropdown adapter. Find this - https://bojanv91.github.io/posts/2017/10/extending-select2-with-adapters-and-decorators - and try to write the same. But problem is this example just include AttachBody, AttachContainer adapters without check the options unlike select2 defaults - https://github.com/select2/select2/blob/develop/src/js/select2/defaults.js. I write the same but stuck into options check:
$.fn.select2.amd.define( 'customDropdownAdapter', [
'select2/utils',
'select2/dropdown',
'select2/dropdown/search',
'select2/dropdown/hidePlaceholder',
'select2/dropdown/infiniteScroll',
'select2/dropdown/attachBody',
'select2/dropdown/minimumResultsForSearch',
'select2/dropdown/selectOnClose',
'select2/dropdown/closeOnSelect',
'select2/dropdown/dropdownCss',
'select2/dropdown/tagsSearchHighlight',
// custom extension
'select2/dropdown/newOption',
],
function(
Utils,
Dropdown, DropdownSearch, HidePlaceholder, InfiniteScroll,
AttachBody, MinimumResultsForSearch, SelectOnClose, CloseOnSelect,
DropdownCSS, TagsSearchHighlight,
NewOption,
) {
// *****************************************
// *** THIS IS HOW SELECT2 DEFAULTS WORK ***
// *****************************************
//
// options = $.extend(true, {}, this.defaults, options);
// if (options.dropdownAdapter == null) {
// if (options.multiple) {
// options.dropdownAdapter = Dropdown;
// } else {
// var SearchableDropdown = Utils.Decorate(Dropdown, DropdownSearch);
// options.dropdownAdapter = SearchableDropdown;
// }
// if (options.minimumResultsForSearch !== 0) {
// options.dropdownAdapter = Utils.Decorate(
// options.dropdownAdapter,
// MinimumResultsForSearch
// );
// }
// ...
// }
//
// *****************************************
// *****************************************
// *** HOW CAN I GET OPTIONS? ***
// const options = ?
// *****************************************
let dropdownAdapter = Dropdown;
// TO SET SELECT2 ADAPTERS
if ( options.closeOnSelect ) {
dropdownAdapter = Utils.Decorate(
dropdownAdapter,
CloseOnSelect,
);
};
// TO SET MY CUSTOM ADAPTERS
if ( options.newOption ) {
dropdownAdapter = Utils.Decorate(
dropdownAdapter,
NewOption,
);
};
return dropdownAdapter;
} );