Menu attributes not rendered when custom building the menu item in twig template

Problem/Motivation

If you create a custom twig template for the menu link and change the output of the menu from
{{ link(item.title, item.url) }}
to e.g.
<a href="{{ item.url }}" "{{ item.attributes.addClass(link_classes).removeClass(item_classes) }}" data-target="#" ><span class="main-menu__link-text">{{ item.title }}</span></a>

the menu attributes that were added through the menu link setting in the backend [0] are not rendered.

I am aware that this is caused by not using {{ link(item.title, item.url) }} but here I need some custom classes which is why I went the a "href..." route.

Any idea of how I could get them into my "a href"? Thanks a lot for this module and your help! This is very much appreciated!

[0]:

Below I have added the menu.html.twig code

{#
/**
 * @file
 * Default theme implementation to display a menu.
 *
 * Available variables:
 * - menu_name: The machine name of the menu.
 * - items: A nested list of menu items. Each menu item contains:
 *   - attributes: HTML attributes for the menu item.
 *   - below: The menu item child items.
 *   - title: The menu link title.
 *   - url: The menu link url, instance of \Drupal\Core\Url
 *   - localized_options: Menu link localized options.
 *
 * @ingroup templates
 */
#}
{% import _self as menus %}

{#
  We call a macro which calls itself to render the full tree.
  @see http://twig.sensiolabs.org/doc/tags/macro.html
#}
{{ menus.menu_links(items, attributes, 0) }}

{% macro menu_links(items, attributes, menu_level) %}
  {% import _self as menus %}
  {% if items %}
    {% if menu_level == 0 %}
      <ul{{ attributes.addClass('menu', 'main-menu__list') }}>
    {% else %}
      <ul{{ attributes.addClass('dropdown-menu') }}>
    {% endif %}
    {% for item in items %}
      {%
        set item_classes = [
          'main-menu__list-item',
          item.in_active_trail ? 'active',
        ]
      %}

      {%
        set link_classes = [
          'main-menu__link-item',
          item.title|clean_class,
          item.in_active_trail ? 'is-active',
        ]
      %}
      {% if menu_level == 0 and item.is_expanded %}
        <li{{ item.attributes.addClass(item_classes) }}>
        <a href="{{ item.url }}" class="dropdown-toggle {{ item.url }}" data-target="#" data-toggle="dropdown">{{ item.title }} <span class="caret"></span></a>
      {% else %}
        <li{{ item.attributes.addClass(item_classes) }}>
        <a href="{{ item.url }}" "{{ item.attributes.addClass(link_classes).removeClass(item_classes) }}" data-target="#" ><span class="main-menu__link-text">{{ item.title }}</span></a>

        {# {{ link(item.title, item.url) }} #}

      {% endif %}

      {% if item.below %}
        {{ menus.menu_links(item.below, attributes.removeClass('nav', 'navbar-nav'), menu_level + 1) }}
      {% endif %}
      </li>
    {% endfor %}
    </ul>
  {% endif %}
{% endmacro %}