CPT archive links in WP menu

gistfile1.php

<?php
  add_action( 'admin_head-nav-menus.php', 'inject_cpt_archives_menu_meta_box');
  function inject_cpt_archives_menu_meta_box( $object ) {
    add_meta_box( 'add-cpt', __( 'CPT Archives' ), 'wp_nav_menu_cpt_archives_meta_box', 'nav-menus', 'side', 'default' );

    return $object; /* pass */
  }

  /* render custom post type archives meta box */
  function wp_nav_menu_cpt_archives_meta_box() {
    /* get custom post types with archive support */
    $post_types = get_post_types( array( 'show_in_nav_menus' => true, 'has_archive' => true ), 'object' );    
    
    /* hydrate the necessary object properties for the walker */
    foreach ( $post_types as &$post_type ) {
        $post_type->classes = array();
        $post_type->type = $post_type->name;
        $post_type->object_id = $post_type->name;
        $post_type->title = $post_type->labels->name . ' ' . __( 'Archive', 'default' );
        $post_type->object = 'cpt-archive';
    }


    $walker = new Walker_Nav_Menu_Checklist( array() );

    ?>
    <div id="cpt-archive" class="posttypediv">
      <div id="tabs-panel-cpt-archive" class="tabs-panel tabs-panel-active">
        <ul id="ctp-archive-checklist" class="categorychecklist form-no-clear">
          <?php
            echo walk_nav_menu_tree( array_map('wp_setup_nav_menu_item', $post_types), 0, (object) array( 'walker' => $walker) );
          ?>
        </ul>
      </div><!-- /.tabs-panel -->
    </div>
    <p class="button-controls">
      <span class="add-to-menu">
        <img class="waiting" src="<?php echo esc_url( admin_url( 'images/wpspin_light.gif' ) ); ?>" alt="" />
        <input type="submit"<?php disabled( $nav_menu_selected_id, 0 ); ?> class="button-secondary submit-add-to-menu" value="<?php esc_attr_e('Add to Menu'); ?>" name="add-ctp-archive-menu-item" id="submit-cpt-archive" />
      </span>
    </p>
    <?php
  }

  add_filter( 'wp_get_nav_menu_items', 'cpt_archive_menu_filter', 10, 3 );
  function cpt_archive_menu_filter( $items, $menu, $args ) {
    /* alter the URL for cpt-archive objects */
    foreach ( $items as &$item ) {
      if ( $item->object != 'cpt-archive' ) continue;
      $item->url = get_post_type_archive_link( $item->type );
    }

    return $items;
  }
?>