Uuid on pivot table in Laravel

Im trying execute laravel migration to create pivot table. I've two models which are defined in relation many to many. Below is method to migration

public function up() {
    Schema::create('api_user', function (Blueprint $table) {
        $table->increments('id');
        $table->integer('api_id')->unsigned()->index();
        $table->foreign('api_id')->references('id')->on('apis')->onDelete('cascade');

        $table->uuid('user_uid')->unsigned()->index();
        $table->foreign('user_uid')->references('uid')->on('users')->onDelete('cascade');

        $table->timestamps();
    });
}

After execute php artisan migrate , I received sql error

SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'unsigned not null, `created_at` timestamp null, `updated_at` timestamp null) def' at line 1 (SQL: create table `api_user` (`id` int unsigned not null auto_increment primary key, `api_id` int unsigned not null, `user_uid` char(36) unsigned not null, `created_at` timestamp null, `updated_at` timestamp null) default character set utf8mb4 collate 'utf8mb4_unicode_ci')

Uuid is storing as varch in DB. Perhaps varchart cannot set as unsigned attribute. Is anothoer way to create pivot table from migration except Laravel-5-Generators-Extended.?

via Chebli Mohamed