How add class to MoreLink in 'Aggregator feed' block?

Hi!

I need to add class to link “More” in Aggregator feed block.

In build method of class AggregatorFeedBlock we have:

        $build['more_link'] = [
          '#type' => 'more_link',
          '#url' => $feed->urlInfo(),
          '#attributes' => ['title' => $this->t("View this feed's recent news.")],
        ];

where ‘#type’ => ‘more_link’, is element describe in class MoreLink

  public function getInfo() {
    $info = parent::getInfo();
    return [
      '#title' => $this->t('More'),
      '#theme_wrappers' => [
        'container' => [
          '#attributes' => ['class' => ['more-link']],
        ],
      ],
    ] + $info;
  }

and output more link in a container template.

How I can add class to link ‘More’, such as

<div class="more-link">
    <a class="MY_CUSTOM_STYLE" href="/aggregator/sources/1" title="View this feed's recent news." hreflang="uk">More</a>
</div>
Drupal version: 


Source: https://www.drupal.org/taxonomy/term/3/feed