some small fixes

src/Controller/RevisionControllerTrait.php

@@ -17,11 +17,15 @@ use Drupal\Core\Entity\EntityInterface;
 trait RevisionControllerTrait {
 
   /**
+   * Returns the entity type manager.
+   *
    * @return \Drupal\Core\Entity\EntityTypeManagerInterface
    */
   abstract protected function entityTypeManager();
 
   /**
+   * Returns the langauge manager.
+   *
    * @return \Drupal\Core\Language\LanguageManagerInterface
    */
   public abstract function languageManager();
@@ -54,9 +58,8 @@ trait RevisionControllerTrait {
    * @param \Drupal\Core\Entity\EntityInterface $entity_revision
    *   The entity to build a revert revision link for.
    *
-   * @return array A link render array.
-   * A link render array.
-   * @internal param int $revision_id The revision ID of the revert link.*   The revision ID of the revert link.
+   * @return array
+   *   A link render array.
    *
    */
   abstract protected function buildRevertRevisionLink(EntityInterface $entity_revision);
@@ -67,10 +70,8 @@ trait RevisionControllerTrait {
    * @param \Drupal\Core\Entity\EntityInterface $entity_revision
    *   The entity to build a delete revision link for.
    *
-   * @return array A link render array.
-   * A link render array.
-   * @internal param int $revision_id The revision ID of the delete link.*   The revision ID of the delete link.
-   *
+   * @return array
+   *   A link render array.
    */
   abstract protected function buildDeleteRevisionLink(EntityInterface $entity_revision);
 
@@ -81,6 +82,7 @@ trait RevisionControllerTrait {
    *   non-current revision, it also provides a link to view that revision.
    *
    * @param \Drupal\Core\Entity\ContentEntityInterface $revision
+   *   The entity revision.
    * @param bool $is_current
    *   TRUE if the revision is the current revision.
    *
@@ -90,9 +92,12 @@ trait RevisionControllerTrait {
   abstract protected function getRevisionDescription(ContentEntityInterface $revision, $is_current = FALSE);
 
   /**
+   * Loads all revision IDs of an entity sorted by revision ID descending.
+   *
    * @param \Drupal\Core\Entity\ContentEntityInterface $entity
+   *   The entity.
    *
-   * @return array
+   * @return mixed[]
    */
   protected function revisionIds(ContentEntityInterface $entity) {
     $entity_type = $entity->getEntityTypeId();
@@ -111,13 +116,12 @@ trait RevisionControllerTrait {
    *   An entity object.
    *
    * @return array
-   *   An array as expected by drupal_render().
+   *   A render array.
    */
   protected function revisionOverview(ContentEntityInterface $entity) {
     $langcode = $this->languageManager()
       ->getCurrentLanguage(LanguageInterface::TYPE_CONTENT)
       ->getId();
-    /** @var \Drupal\content_entity_base\Entity\Storage\RevisionableStorageInterface $entity_storage */
     $entity_storage = $this->entityTypeManager()
       ->getStorage($entity->getEntityTypeId());
 
@@ -181,13 +185,11 @@ trait RevisionControllerTrait {
    */
   protected function getOperationLinks(EntityInterface $entity_revision) {
     $links = [];
-    $revert_permission = $this->hasRevertRevisionAccess($entity_revision);
-    $delete_permission = $this->hasDeleteRevisionAccess($entity_revision);
-    if ($revert_permission) {
+    if ($this->hasRevertRevisionAccess($entity_revision)) {
       $links['revert'] = $this->buildRevertRevisionLink($entity_revision);
     }
 
-    if ($delete_permission) {
+    if ($this->hasDeleteRevisionAccess($entity_revision)) {
       $links['delete'] = $this->buildDeleteRevisionLink($entity_revision);
     }
 

src/Controller/RevisionOverviewController.php

@@ -18,6 +18,13 @@ use Drupal\entity\Revision\EntityRevisionLogInterface;
 use Drupal\user\EntityOwnerInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
+/**
+ * Provides a controller which shows the revision history.
+ *
+ * This controller leverages the revision controller trait, which is agnostic to
+ * any entity type, by using the new interface
+ * \Drupal\entity\Revision\EntityRevisionLogInterface.
+ */
 class RevisionOverviewController extends ControllerBase {
 
   use RevisionControllerTrait;
@@ -77,6 +84,15 @@ class RevisionOverviewController extends ControllerBase {
     }
   }
 
+  /**
+   * Generates an overview table of older revisions of an entity.
+   *
+   * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
+   *   The route match.
+   *
+   * @return array
+   *   A render array.
+   */
   public function revisionOverviewController(RouteMatchInterface $route_match) {
     return $this->revisionOverview($route_match->getParameter($route_match->getRouteObject()->getOption('entity_type_id')));
   }
@@ -87,23 +103,20 @@ class RevisionOverviewController extends ControllerBase {
   protected function getRevisionDescription(ContentEntityInterface $revision, $is_default = FALSE) {
     /** @var \Drupal\Core\Entity\ContentEntityInterface|\Drupal\user\EntityOwnerInterface|\Drupal\entity\Revision\EntityRevisionLogInterface $revision */
 
-    if ($revision instanceof EntityOwnerInterface) {
-      $username = [
-        '#theme' => 'username',
-        '#account' => $revision->getOwner(),
-      ];
-    }
-    else {
-      $username = '';
-    }
-
     if ($revision instanceof EntityRevisionLogInterface) {
       // Use revision link to link to revisions that are not active.
       $date = $this->dateFormatter->format($revision->getRevisionCreationTime(), 'short');
       $link = $revision->toLink($date, 'revision');
+
+      $username = [
+        '#theme' => 'username',
+        '#account' => $revision->getRevisionUser(),
+      ];
     }
     else {
       $link = $revision->toLink($revision->label(), 'revision');
+      $username = '';
+
     }
 
     $markup = '';

src/Routing/RevisionRouteProvider.php

@@ -118,9 +118,7 @@ class RevisionRouteProvider implements EntityRouteProviderInterface {
         '_controller' => '\Drupal\entity\Controller\RevisionOverviewController::revisionOverviewController',
         '_title' => 'Revisions',
       ]);
-      $route->addRequirements([
-        '_entity_access_revision' => "$entity_type_id.list",
-      ]);
+      $route->setRequirement('_entity_access_revision', "$entity_type_id.list");
       $route->setOption('entity_type_id', $entity_type->id());
       $route->setOption('parameters', [
         $entity_type->id() => [

tests/src/Kernel/RevisionBasicUITest.php

@@ -43,6 +43,9 @@ class RevisionBasicUITest extends KernelTestBase {
     \Drupal::service('router.builder')->rebuild();
   }
 
+  /**
+   * Tests the revision history controller.
+   */
   public function testRevisionHistory() {
     $entity = EnhancedEntity::create([
       'name' => 'rev 1',