2amigos/yii2-selectize-widget: how to set up default value when options are customized

Selctize.php

<?php

namespace common\modules\appearance\widgets\backend;

use yii\web\JsExpression;

/**
 * Selectize customization
 *
 * @author Michail Urakov
 */
class Selectize extends \dosamigos\selectize\SelectizeDropDownList
{

    /**
     * @var array Items array (value => description pairs)
     */
    public $items = [];

    /**
     * {@inheritdoc}
     */
    public function init()
    {
        $items = [];
        $items[] = ['name' => '', 'description' => 'NOT_SELECTED'];
        foreach ($this->items as $name => $description) {
            $items[] = compact('name', 'description');
        }
        $this->clientOptions = [
            'valueField'       => 'name',
            'labelField'       => 'description',
            'searchField'      => ['name', 'description'],
            'persist'          => false,
            'create'           => false,
            'options'          => $items,
            'maxItems'         => 1,
            'allowEmptyOption' => true,
            'items'            => [$this->model->{$this->attribute}], //IT'S VERY IMPORTANT to set up this otpion if you expect default value will be empty
            'render'           => [
                'option' => new JsExpression('function(item, escape) {'
                        . 'return "<div><div><b class=\\"text-turquoise\\">"'
                        . ' + item.description + '
                        . '"<\\/b><\\/div>'
                        . '<div class=\\"text-concrete\\">"'
                        . ' + (item.name !=="" ? item.name: "-") + '
                        . '"<\\/div><\\/div>";'
                . '}'),
                'item'   => new JsExpression('function(item, escape) {'
                        . 'return "<div class=\\"item\\" data-value=\\""'
                        . ' + item.name +'
                        . '"\\" data-desc=\\""'
                        . ' + item.description +'
                        . '"\\">" + item.description + "<\\/div>";'
                . '}'),
            ],
        ];
        parent::init();
    }
}