Create link with attributes in Drupal 8

url.php

<?php

$url = Url::fromRoute('node.add', array('node_type' => $content_type));
$url->setOption('query', \Drupal::destination()->getAsArray(),);

$link = [
  '#type' => 'link',
  '#title' => t('Add !content_type content', array('!content_type' => $content_type)),
  '#url' => $url,
  '#attributes' => [
    'class' => ['button', 'button-action', 'button--primary', 'button--small'],
  ]
];