nested navigation with in template variables.

nav.twig

  {% set nav = [
  {"href": "http://1.com", "name": "link1","sublinks":null},
  {"href": "http://1.com", "name": "link2","sublinks":null},
  {"href": "http://1.com", "name": "link3","sublinks":
    [{"href": "http://1.com", "name": "link 3.11","sublinks":null},
    {"href": "http://1.com", "name": "link 3.22","sublinks":
      [{"href": "http://1.com", "name": "link 3.11","sublinks":null},
       {"href": "http://1.com", "name": "link 3.22","sublinks":null}
      ]
    }]
  },
  {"href": "http://1.com", "name": "link4","sublinks":null},
  {"href": "http://1.com", "name": "link5","sublinks":null},
  ] %}


  {% macro menu_links(items, outside, inside) %}
  {% spaceless %}
      {% for item in items %}
          <{{inside}}>
              <a href="{{ item.href }}">{{ item.name }}</a>
              {% if item.sublinks %}
                  <{{outside}}>
                      {{ _self.menu_links(item.sublinks, outside, inside) }}
                  </{{outside}}>
              {% endif %}
          </{{inside}}>
      {% endfor %}
  {% endspaceless %}
  {% endmacro %}

  {% import _self as navi %}

  <ul class="main-menu">
      {{ navi.menu_links(nav,'ul','li') }}
  </ul>

I had to add another {% import _self as navi %} inside the macro, and then change _self.menu_links to navi.menu_links for this to work in Craft 3.