Issue #2368957 by mikispeed: Fixed Set class on MoreLink as array instead as string.

core/lib/Drupal/Core/Render/Element/MoreLink.php

@@ -8,7 +8,7 @@
 namespace Drupal\Core\Render\Element;
 
 /**
- * Provides a link render element.
+ * Provides a link render element for a "more" link, like those used in blocks.
  *
  * @RenderElement("more_link")
  */
@@ -24,7 +24,7 @@ public function getInfo() {
       '#title' => $this->t('More'),
       '#theme_wrappers' => array(
         'container' => array(
-          '#attributes' => array('class' => 'more-link'),
+          '#attributes' => array('class' => array('more-link')),
         ),
       ),
     ) + $info;