protected function getRevisionDescription(ContentEntityInterface $revision, $is_current = FALSE)
 {
     /** @var \Drupal\Core\Entity\ContentEntityInterface|\Drupal\user\EntityOwnerInterface $revision */
     if ($revision instanceof EntityOwnerInterface) {
         $username = ['#theme' => 'username', '#account' => $revision->getOwner()];
     } else {
         $username = '';
     }
     if ($revision instanceof ExpandedEntityRevisionInterface) {
         // Use revision link to link to revisions that are not active.
         $date = $this->dateFormatter()->format($revision->getRevisionCreationTime(), 'short');
         if (!$is_current) {
             $link = $this->l($date, $revision->urlInfo('revision'));
         } else {
             $link = $revision->link($date);
         }
     } else {
         $link = $revision->link($revision->label(), 'revision');
     }
     $markup = '';
     if ($revision instanceof EntityRevisionLogInterface) {
         $markup = $revision->getRevisionLog();
     }
     if ($username) {
         $template = '{% trans %}{{ date }} by {{ username }}{% endtrans %}{% if message %}<p class="revision-log">{{ message }}</p>{% endif %}';
     } else {
         $template = '{% trans %} {{ date }} {% endtrans %}{% if message %}<p class="revision-log">{{ message }}</p>{% endif %}';
     }
     $column = ['data' => ['#type' => 'inline_template', '#template' => $template, '#context' => ['date' => $link, 'username' => $this->renderer()->renderPlain($username), 'message' => ['#markup' => $markup, '#allowed_tags' => Xss::getHtmlTagList()]]]];
     return $column;
 }